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Distribution authorized to U.S. Gov't.agencies and their contractors;Administrative/Operational Use; "Aug 1968.Other requests shall be referred to AirForce Aero Propulsion Lab.,Wright-Patterson AFB, OH 45433. NOFORN.

AUTHORITY31 Aug 1980, Group-4, per documentmarking; AFWAL ltr, 14 Dec 1983

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AFPLTl-6-8CONFIDENTIAL

Part I

111111111 (UNCLASSIFIED)

=3XPLORATORY DEVELOPMENT OF REDUCED LENGTHý0 TURBO-PROPULSION COMBUSTION SYSTEMS

Part 1. Preliminary Component Design and Development

J. J. Simon D. A. MocNaughtonR. J. Stettler J. T. Wyrobek

Alison Division * Generasl Motors

TECHNICAL REPORT AFAPL-TR-68-8, PART I

August 1968

GROUP 4

* Downgraded at 3 year intervals;declassified after 12 years

SPECIAL HANDLING REQUIRED

NOT RELEASABLE TO FOREIGN NATIONALS

The information contained in this documentwill not be disclosed to foreign nationals ortheir representatives.

This material contain% information affecting the national defense of the

United States within the meaning of the tspionage laws, Title 18, U.S.C..

Sections 793 and 794, the transmission or revelation of which in any

manner to an unauthorized person is prohibited by law.

* Air Force Aero Propulsion Laboratory,Air Force Systems Command

*Wright-Patterson Air Force Base (7Ohio 45433

AFLC-WPAF8-OCT 68 50 ICONFIDENTIAL

NOTICE

When Government drawings, specifications, or other data are used for any purposoother than in connection with a definitely related Government procurement operation,the United States Government thereby Incurs no responsibility nor any obligationwhatsoever; and the fact that the Government may have formulated, furnished, or inany way supplied the said drawings, specifications, or other data, is not to be regardedby implication or c.'Uhcrwise as in any manner lit 3nsing the holder or any other personor corporation, or conveying any rights or permission to manufacture, use, or sell anypatented invention that may in'any way be related thereto.

This is a reprint copy with Section IV, paragraph 6, pages 72 through 80 deletedfor proprietary reasons.

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|!S

CONFIDENTIAL

AFAPL-TR-68-8

Port I

(UNCLASSIFIED)

EXPLORATORY DEVELOPMENT OF REDUCED LENGTH

TURBO-PROPULSION COMBUSTION SYSTEMS

Part I. Preliminary Component Design and Development

J. J. Simon D. A. MacNaughton

R. J. Stettler J. T. Wyrobek

3 'EAR IlTrMALtSI~~ ~ '77 i"' 12 YLIRS

GROUP 4

Downgraded at 3 year intervals;

declassified after 12 years

SPECIAL HANDLING REQUIRED

NOT RELEASABLE TO FOREIGN NATIONALS

The information contained in this documentwill not be disclosed to foreign nationals ortheir representatives.

This material contains information affecting the national defense of the

United States within the meaning of the espionage laws, Title 10, U.S.C.,

tections 793 and 79A, the transmission or revelation of which in any

manner to an unauthorized person is prohibited by lIw.

"STATFMVT #2 CIaSSIFIED

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d eachjtt ~, :c 'n ationals MY

0.u aly wiLhL ~ ~ 0

CONFIDENTIAL

CONFIDENTIALTHIS fAGE IS UNCLASSIFIED

FOHFW()IiI)

(U) lPresent .nithustion system technology using high pressure fuel nozzles in can-type crm, -

hustors cannot cope with the advances in turiopropulsioni engines. To maintain pace with

engine advances, the combustion systeri (aniular contbiistor) will require a low pressure fuel

system unaffected by contaminated fuel and an integrated difruser-comhustor to reduce weipht

and siae. The system will also require a high crointjus.-.lor Iitoire air flow% in conijmnction % ith

premix fuel modules to provide increased temperatures with uniform distribution, low prps -

sure loss, and high combusitor efficiency.

(U) Allison [)jvision of General Motors Corporation undertook the exploratory development of

reduced length turbopropulslon combustion systems for the United States Air Force, Air ForceSystems Command, Aero Propulsion Laboratory (AFAPL), Wright-Patterson Air Force Base,

Ohio. This work under Contract F33615-67-C-1939, Project No. 3066, Task No. 306603, was

monitored for the Air Force by Mr. Robert E. llenderson/APTC and Mr. Morris D. Louick/

SEKNB.

(U) The Phase I report draft was aubmitted on 15 January 168 and covers the design, fabri-

cation, and testing during the period from 1 July 1967 through 31 December 1967.

The Allison number for this report is EDR 5610.

(M) This report contains no classified information extracted from other classified documents

other than the periodic progress reports published in accordance with this contract.

(U) Publication of this report does riot constitute Air Force approval of the report's findings

or conclusions. It Is published only for the exchange and stimulation of ideas.

E RNEST C. SdMý0oNChief, Turbine Engine Dtvision

AF Aero Propulsion Laboratory

CONFIDENTIAL

UNCLASSIFIED

ANOW llion___________

UNCI.ASSIFIII) A BS'RIA(CT

Advanc.ed design turbo-propulsion engint.s for future air.rI'ft rtluis. a -,!wal. t. high io-rftur-

mant'e combustion systelt for high thrust-to-weight ration and an lncrease-d Ievel- of rp-liability.

To attain this goal. two vonvepts ba.ed on maxilnumn cunibustor do•e- airflow are b-ing .v-4

velopid. The first is an integration of the diiffuis.r and combusto)r to achirvv minimum length

and maxinium efficiency with snvoke fre.. operation. The. sevonti is to avhievs.. imprrwe* fuel

injec'tion using a high density premix fuel injection technique to obtain a4"-epfahbl o.xit tmpvra-

ture patterns in a high temperature rise combustor. The fuel inje.tcoet tech-ique is the de-

velopment of single modules for premixing of low pressure, fuel and high vw.;ý.ty air ahead of

the combustor dome. These modules are capable of accepting contaminate-d fuels and can be

combined to permit testing as sectors of a full annular combustor.

Initial testing of the various fuel injection premix modules and different designs of the integrated

diffuser-combustor under Phase I of this program has verified the soundness of the Concepts

being developed. Based upon these results. the most promising premib modules and the best

diffuser-combustor design will be combined as sectors of a full annular combustor for further

evaluation.'

Distribution of this abstract is unlimited.

UNCLASSIFIED

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• .,•~~Allison r ,

TABLE OF CONTEN'TS

Section Title Page

I Introduction ................. .......................................

Ii Flow Path Design Factors .................... .......................... 3

III Integrated Diffuser-Combustor . ......... ......................... 13

1. Requirements ................... ............................ 13

2. Aerodynamic Design Studies ....... .................... ..... 13

3. Mechanical Design ............ . .... .................. .... 17

4. Design Criteria and Predicted Performance .............. ... 38

5. Analysis ...................... .............................. 39

IV Premix Fuel Injection ............. ............................ ..... 51

1. General Considerations .......... ...................... ..... 51

2. Vee Gutter Module ........... ......................... .... 60

3. Swirl Chamber Module ......... ....................... ..... 63

4. Conical Fuel-Air Spreader Module ..... ................ .... 66

5. Double Reversal Chute Module ............ ................... 69

6. Venturi-Vortex Module (Deleted. See Notice Page.) .......... 72

V Contaminated Fuels Test ............. .......................... ..... 81

VI Fuel Injection Computer Program ........ ..................... ..... 83

VII Test Results ................ ................................. ..... 85

VIII Phase II Program ...................... .............................. 111

IX References ........................................................ 113

X Bibliography ................ ................................. .... 115

Uv

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i.1ST OF IILLISTRATIONS

Figure Title Page.

I Complete flow path of the initial design tomp o-nnts. ...... ............. 5

2 .•aling to 4X size using modular conce,.pt ...................... . ...

3 lEstimated Il)oss incurred in dumping diffuser discharge velocity ...... 9

4 Mean droplet diameter versus atomization velot'ity for Varioew

equivalent-t ratios ........... ................... . ........ 10

5 Predicted compressor dischargu pr,,ssure and velocity profiles . 15

6 Dhffuser performance data for "A", "B",- "C", and "1l"diffusers ..... 16

"7 Combustion rig diffuser flow path ........... ...................... 18

8 Estimated diffuser los ...... ................ . . . ...... 18

9 Diffuser area versus length of diffu4er, "A"-diffuser ........... 19

10 Flow visasalizatinn rig ............. ............................. 19

11 Combustion rig "B" diffuser flow path ...................... 22

12 Diffuser area versus length of "B"-diffuSer ................. 23

13 Combustor rig diffuser "C" flow path ................ ... . . ... 24 •"

14 Area progression versus diffuser length "C"-dlffuser. upper path . . .. 29

15 Area progression vertus diffuser length "C'."-diffuser, lower path . . .. 30

16 Diffuser area versus length of diffuser 'D"-diffuser. ;uel-air spreader

module, upper path ....... ........................... ..... 31

17 Diffuser area versus length of diffuser "D"-dlffuder. fuel-air spreader

module, lower path . . . . . ....... . . . . . . . . .. . . 32

to Upper path of "D"-diffuser area versus length of diffuser . . . . . . 35

19 Lower path of "D'-diffuser area versus length of diffuser. ..... ... 36

20 Combustion rig "A" diffuser flow path ....... ......... ....... 36

21 Combustion rig "D" diffuser flow path ........... . . . * .... 37

22 Diffuser parameters versus length of diffuser, "A"-diffuser ....... 40

23 Diffuser parameters versus length of diffuser, "B"-difftser, upper path. 41

24 Diffuser psram.ters versus length of diffuser, "B"-dffuster,

lower path ... ................. . . . . . . , .* .C -. . a. 42

25 Diffuser parame.ters versus length of diffuser, "C"-diffuser,

lower path .................. .. .. . . .. . .. .& * . .. 43

26 Diffuser parameters versus length of diffuser. 'C"-dlffuser.upper path ............................. . . . . ......- 44

27 Diffuser parameters versus length of diffuser. "D"-diffuser,

lower path ......... ..................... . & . .* .... 45

28 Diffuser parameters versus length of diffuser, "D"-diffuser,upper path .... ....................... . . . . . .. .. 46

vii

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Figure Title Page

29 Single-module rig-rold flow configuration ..... ................. ..... 53

30 Single-module rig-hot flow configuration ......... .......... .... . 55

31 Airflow split in premix rombustion systems .................... .... 57

32 Mean droplet diameter versus temperature for fuel and water . . .. . . 58

33 Camera and lighting for droplet photography ........ ................ 59

34 Three dimensional isotherm plot ........... ...................... 61

35 Vee gutter modUle .............. .............................. 62

36 Vee gutter droplet field ................. . . . . ............. ...... 64

37 Swirl chamber module ............................... 65

38 Swirl rhamoer module droplet field .......................... 67

39 Conical fuel-air spreader module ........... ...................... 68

40 Conical fuel-air spreader module droplet field ........ . ... .... 70

41 Dougle reversal chute module .......... ..................... ..... 71

42 Prototype venturi-vortex configuration ......... ................... 73

43 Venturi-vortex prototype flowing air and fuel through the venturi only . 73

44 Venturi-deflector plate-vortex with no orifice plate .... . ...... ....... 74

45 Venturi-deflector-vortex witl orifice. ......... .................... 74

46 Venturi-deflector-vortex with orifice ............ ............ .. 74

47 Airflow vs pressure drop at various stage% of assembly ...... .......... 76

48 Venturi-vortex module, 22 *................. . . . ....... 77

49 Venturi-vortex module, # * 5 ........... ........................ 77

50 Venturi throat and vortex tube areas .......... .................... 80

51 Test equipment configuration and contaminant for fuels contaminated

per MIL-E-5007B .............. ............................ 82

52 Pressure drop versus Mach number under cold and burning conditions . 88

53 Chromatograph efficiency versus fuel-air ratio at 2 and 6

atmospheres ....... .............................. 89

54 Isotherm and efficiency, profiles at the burner sector mean depth

for the vee gutter module ........................... 1

55 Pattern factor versus overall fuel-air ratio at 2 and S atmospheres . . 93.

56 Inlet pressure versus fuel-air ratio at lean blowout . .. . . . . .. . ..4

57 Flow before ani after contaminated fuel testing ................. * ...... 96

58 Flow tracers showing flow through "A" diffuser and into premix are& . . 97

59 Test rig flow paths ......... .............. .......... .... 99

60 "A" di'fuser pressire losses and dump losses versus Mach number . . . 102

$I Velocity and pressurs, profiles from "A" diffuser ........... 103

62 Velocity and pressure profiles from "A" diffuser ....... ............ 104

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Figure Title Page"

63 "B" diffuser upper passage profiles ................. . . . 105

64 "B" diffuser lower passage profiles ........... ......... 106

65 "B" diffuser upper passage profiles .............. . 107

66 "B" diffuser lower passage profiles .................... 108

67 "B" diffuser pres3ure losses and dump loss-s versus Maeb number . . .

LIST OF TABLES

Table Title Page

I ~Design features ............ ............................... . 4

1I "A": Annular single path dump diffuser with inlet vanes ................ 20

I!t "B": Annular two path dump diffuser with circumferential splitter

and inlet vanes ............................ 25

IV "C": Channeled two path diffuser with circumferential splitter~and

integrated bell-shaped inlet vane passages .................. . 27

"V "D": Channeled two path diffuser with cirvumferential splitter and

integrated bell-shaped inlet vane passages .................... 33

VI Venturi-vor~rx module requirements ............ ......... 78

VII Venturi and vortex airflow ....... ................. . ........ 78

VIII Observations and comparisons of modules ............. . ... ........ 87

IX "A" and "B" diffuser design and test data .... ........ . . . . ... . 98

ix:

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Allson___JI

".:~~~ I lN.TRODUJ•IO:

"(C) T.e rapid advan:es in turbo-propuls!on tech.noloa' over the past &everal

years have placed an ever-increasir.n de.mand upon co:*ustion system performance.

Puture co•bustion systems viii be required to support Air Force missions

rarZin3 from subsonic long erzurance systems, advanced supersonic VTOL and

strategic-tactical systems, to hypersonic systems for both accelerator and

cruise vehicles. To meet effectively the requirements of these advanced

mission types, combustors must have the operational flexibility to accept

vide variations in compressor discharge pressure, te-perature, arn air flow

while providing an acceptable exit temperature profile with minimum pressure

loss and good combustion efficiency. Furthermore, advancred combustion systems

must be lightweight and capable of accepting contanmnated fuels while maintaining

stable operation over the entire range of Zlight operating conditions.

Exploratory investigations accomplished under Air Force Contract A733(615)-130O

have indicated that high temperature rise combustion systems approaching

stoichiot-etric exit conditions will require Increased burner dome flow In

conjunction vith Improved fuel injection techniques. Increased dome flow and

high density fuel injectlon can provide as much as a 40 percent reduction in

combustor length because of increased fuel-air mixing in the combustion zone.

However, It is recognized that as the minimum combustor lenGth is approached,

combustion efficiency and exit temperature profile begin to deteriorate.

Therefore, improved fuel injection tec'hiques are desirable to =aintain

good fuel-air mixing thus insuring that combustion efficiency ard exit

temperature profile are maintained at acceptable perfor-.ance levels. Arnq

*!

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Ammuon___________

further reduction in -omoustion system length must be accomplished through

sore effective utilization of the burner inlet diffuser which currently

occupiez a large percentage of the overall length of the .ubustlun system.

It is the purpose of this exploratory research And developmet program to

Investigate component techniques whi'h vi.I minimize the 'Werall length .X

a combustion system free the compressor exit to the inlet of the turbine.

Various integrated diffuser/combustur approaches will be InestIgAted with

e@1etis oa high dome flow, high temperature rise systems with exit tempera-

tures approaching 3500"F using J.1 fuels. In addltion, it is intended that

low pressur, differential fuel Injection techniques be investigated to

improve the contamination resistance of the fuel nozzles sad enhance further

reductions in the complexity and weight of the fuel system. Tradeoff

investigatiocs will be conducted to establish the optimm combustion

system for various defined mission objectives. This progrea will provide

the teWheoloa required to design efficient combustion systems with wide

operating range and significantly reduced diffuser/combustor length. These

systems will have predictable performnce characteristics for advanced

propulsion systems.

(C) The objectives of this exploratory research program are:

* To increase the level of operational reliability for turbo-

propulsion systems

0 To reduce coustion system weight and volor

* To provide the technology necessary to reduce the overall length of

the combustion system by the,Spplietstlon of advanced dItfuser/ecmbuat•-r

concepts snd fuel injection techniques.

2

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i . -II I III I

______________Allison______________

11 FLCW PATH DErc1l FAC'YC"S

(C) PhMa I of this exploratory development program cunsisted of research

Investigations conducted to design and evaluate various combustion system

eonfgiuratlna or roedaad di•fusar-co,.busator lvn,ýth. It anlt Included

investigAtions of fuel injection techniques of low pressure differential

systems that would be capable of accepting contaminated fu'els.

(C) This inttial phase is the first of a c;mprehensive three phase program.

The comprehensive program spans an exploratory pressure range of 0.3 to

20 atmospheres and inlet temperatures to 1200"F, vwth the following design

point performance goals:

0 A combustion efficiency, rlb 2 984

* A pressure loss, .4-P/P •

0 An average exit temperature, T ' 3500"?

• A uxisum temperature rise, T 2aC0"*7

T T0 An exit temperature profile,• - -gAvg.& a .15 to .20

T T,Avg -i

* To demonstrate a performance and sizing computer program, sensit•ve

to mission and engine operating corndtions, for the combustion

system that can be substantiated by test.

(C) The hardvare required to conduct the initial pase of this program vas

sized to reflect a continuity of results with Phase 11 and Phase III.

The initial designs; therefore, are based on facility cspabillties to

enable the complete air flow, temperature, and pressure demonstration

of a 120 sector of an annular coebustion system. This sizing was a&so

3

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Allilon __ _ _ _ _ _ _ _ _ _ _

•nfluenccd by nent ark! exit corlitl-ns erAizlf.c .r Force m'-2s.on-

used as 6'.ide l'nes. T1::ese mision:, arv:

* binic lon endjranct:

SJv-cd std rso. Ltrateglc/!a:t,:a"

• Hkyp.rstniA: Azc-.erat~ r and cru:e

(C) Tht four missiuns verM exl-n.ind and an .niet velocity ot 54 tt/sec

and ex it vel,,ity of 700 ft/sec vere wle:tel Las a representative

condition. The initial da:A.--n festurve are liated in !Able 1 and

a complete flv pth of the initial design components Is shown In Figure

I.

(C) TABLE I DEOS-EN 7rLJR-S

Feature V e

Diffusor inlet velocity f rt/sec

Diffuser outlet velotity 304 ft/0"C

Diffuser length '.5 in.

Diffuser area ratio, outlet to inlet 1.78

Diffuser pressure drop ( 1.-5

Premix module length 1.8 in.

Premix module neat load 40 X.O` B:Jiata-.zu.ft-hr.

Combustor vOlUme heat lo*d ib.i XL" S.:/at.-:u. nt-h"r

Pitch lire d.ameter 1I.... ".

Coabustor hil• 4bt. .

Combust~or length 7.35 in.

Cobu•sor volume . c8 e•ft.

4

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Jft - -Z IS AM

1.~' 6*O

01 of FA B zzJ

zýrs

F~gure 1. omltflwptofteItildsgcmoen.

~ I ONFDEH

4v 9 /

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T1' get A *TRP V t V

-f4#e -. 1

CO .I2NIA 224

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Allison

Co:nbu.,Lor domL= area 13i4 .5 s6,. In.

Combustor rer'erenc,, area 158 sq. in.

Co:nbustor le±nýth/ hu.t ratio !.5

Combu:•tor exit velocity-hot maximnu 7(0 ft/hec

Combustor and modiule pressure drop 3.5

(C) The use of premix fuel muduies makes the combustion syu.tem condiclve

to scaling for other sizes. From the initial design a 4X s~ze scaled

sector version will be fabricated. Th.s will be used to determine the

effects of scaling on the diffuser, the premix modules, and the

combuator. Figure 2 shows a comparison of the initial and sc.-cd versions.

This evaluation Is a part of the Phase II portion of this program.

(C) The air velocity at the premix 1lret was established at 304 it/sec based

on two considerations. These considerations were the pressure loss

dumping into the combustor as described in Figure 3 and the small advantage

which could be inc'urred by utilizing adaitional air energy for atomization

as shown in Figure 4. The areas through the premix module, priuary zone,

and dilution air passages were designed to maintain the velocity of 304

ft/sec.

(C) The air flow to the combustor is a straight flow through the combustor nead

plate or dome. This flow path, in several annu.ar combustors, nas demon-

strated an advantage in establishing a •...•nced primary zo'ne a-.d in

reducing the diffuser length. The combust-r was desigacd to rcflect

present technology as use, witc high ,- --.sure fue. atomizers. The combustcr

volume reflects a heat loading of i6.4 X -O6 Btu/atwu.-cu .t-hr. at a

7

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"-Allison

I I

n44

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Figure 2. Scaling to 4X size using modular concept.

8

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r 3

09

C D. A

.4

2

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/aoo 30o -qo -S'oo 600D~in velocity *-/:.Sec.

S~Figure 3. Estimated loss incurred in dumping diffuser discharge velocity.

= _--_CONFIDENTIAL

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P,./" ter,* IV U tl

100

re401P

ý*/c ity- frt /sec.

Figure 4. Mean droplet diameter versus atomization velocity for various equivalence ratios.

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,�___________________Alflson_____,____

pressure of tventy ata.7sp•,res.

(C) The initial sysacu vos designed to permit replsce.-ent of each c•o•onrýt

for cloce eva•luation of =,difI.-atiLns &:.d• des!1g linItation•s. RI,; arAd

Component ha-rdware for co-14 flow testing w~re desiened to enable the co-.;ýratlve

evaluation of char4;es leadirg to reduced diffuser, length The cold flow

test rig was &19e3 designed to est•ablish the. varlatiant In fuel stomization

described by air velocity, air direction, and type of atcmization surface.

Not or burnIng test equip.ent was designed" to evaluate the reaction l.e negt.h'

the mixing of the dilution air for teeperat-4re traverse q~alit', and t.he

beat rejection to the aide walls that accompanies the hieh doce flow premix

11

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AIlltlon'___________

III IECTEC?.ATED DIP'3Y--R-CC'3U.2t2'I

1. Requirements

(C) The intecratian of the diffuser acd co6bustor Is to achieve

aUnimum lenth and maxl-un aerodyt=lc efriccacy. Selectloa

of the Integrated diffuser-co=bustor configurations was based on

aerodynamic design studies. The evaluation of t.ese configurations

was based on diffuser performance characteristics as e'fectei by

variations in:

* Shape factor

* Mach number

0 fno factor

* Diffuser vidth to len3th ratio

* Axial area progression

* Inlet to exit area ratio

(C) This section describes the analytical design s'tuy of an Integrated

annular diffuser-combustor capable of recovering pressure vith a mass

flov of 64 lb/sec at a discha-r'e pressure of 29I, psi. and * Vach

ntuber of 0.296. The major portion of the air flow (&$) is directed

through the dome. The rematning portion (16) is split in the

upper passog (9%) and the lower passage (") az is used for conbustor

eooling.

2. Aerodyu&-•c Des:gn Studies

(C) A feasibility study was made vith the follovlnj requirements as

related to optizun engit and combustor ;erforz-ance:

13

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, Allison _

"* Shortest possible 1enzth

"* Integration of air diffusing pLth within the fuil

atomization module

"* Low prne3ure loss

"* Uniform velocity profile at the diffuser exit

(C) A parcietric study was made of pressure recovery (Cp) versus

width to length ratio (N/L4R) and inlet to exit area ratio.

This was based on performance data collected from actual tests

of many diffusers. This experience on performance of engine

diffusers operating behind axial flow compressors was correlated

with the work in References (1, 2, 3 and 4). This correlation

includes the use of a radial velocity profile ratio (Vmax/Vavg

= 1.15) at the diffuser inlet. See Figure 5 for the typical

engine diffuser radial velocity profile. The variations in

performance resulting from an un:desirable velocity profile at the

inlet to the diffuser are shown in Figure 6. These curves were

established as a result of correlated test data with theoretical

research performance based on many different diffusers.

(C) The aerodynamic design studies led to the selection of four

different diffuser designs. These diffusers must perform at a

wide range of Mach nubers and provide a uniform circumferential

exit velocity profile. The optima of diffuser geometry and peak

pressure recovery correlations were established by takinrg the

momentum losses and reaction rates, which affect the combustors,

into consideration. The aerodynamic analysis includes the

14

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10'

If ix o

a: 7

oo

46l

Vl

6 t. .

0

15

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3.0

"•"-~~ ~~ OAwqp. -eC" in¢cer o'/

v 0-diff'ser maute

4. 7 a 9 1

.'34. o "IA' dif9 is

D~ffuser length to in/eZ widthd ratio f VfueR

Figure 6. Diffuser performance data for "A", "B", "C", and "D" diffusers.

16

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Al ninon

computed performances of the four diffuser designs.

3. Mechanical Design

(C) Four diffusers were designed. The firat, an "A" dirfuser is a

single passage, straight dump, annular diffuser which is bounded

on the Inner and outer sides by a conical surface and has a

cross-sectional form of a ring. This design is shown in Fip re

7. The design parameters for optimum size and predicted

performance are shown In Table II and Figures 8 and 9.

(C) The flow visualization rig with the "A" diffuser is shown in

Figure 10. A straight section preceding the diffuser inlet

provides a smooth inlet flow with symmetric boundary layers.

Pressure distribution measurements are taken at the diffuser

inlet and outlet. A five element pressure rake and two static

pressure taps at each location give the pressure distribution

for comparison with predicted analytical values. The installation

of plastic models of the other diffuser designs provide similar

data.

(C) The combustion rig with the "A" diffuser is also shown in Figure 7.

The straight section and the diffuser section of this rig can be

varied in length by the use of interchangeable sections. This

will allow the diffuser angle to vary. This design allows

a maximum number of test configurations with a minimum of hardware

fabrication. All four diffusers will be tested on this rig. This

17

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Moverr diahW5

Figure 7. Combustion rig diffuser flow path.

S 2.4A

4'~ ".

/VO B 11.Dd%let.

I*3

Zoo~ 280 316 0 /,10 Sb00

Di-ffusei- exit- VeIClo '%.*,4

Figure 8. Estimated diffuser losses.

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55S O- -- - - - . .. , 0/0--- -- 0-. .. -- _

35'

30 0.5 4.0 Z-0a~ 2.5 3.0 3.5 4%0 *-S

Len,7ith of diffuser --j7,c/es

Figure 9. Diffuser area versus length of diffuser, "All-diffuser.

WeIt discharge

Fecigue1.Fooisaiainrg

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(C) Table IT

"A": Annular oingle path dump diffuscr with inlet v"ns,,

Airflow Wu lb/sec 64.

Compressor discharge pressure Pto pula 302.8

Diffuser inlet total pressure Ft, psia 294.0

Diffuser inlet static pressure Pal psia 276.7

Diffuser inlet temperature T1 "R 1460

Diffuser inlet velocity avg. V1 Ft/sec 548

Diffuser inlet Mach number M0.296

Diffuser inlet width 6R 1 in .709

Diffuser inlet area A1 in2 2.19

Diffuser length N in 4.5

Diffuser length to inlet width ratio N/&R 6.35

Diffuser exit to inlet area ratio AR 1.78

Diffuser inlet velocity ratio Vmax/Vavg 1.15

Pressure recovery CP 40.5%

Diffuser discharge pressure Pt 2 psia 288.9

Diffuser discharge pressure P82 psia 283.7

Diffuser outlet velocity V2 ft/sec 304

Diffuser outlet VAch number M02 .163

Diffuser outlet area f in 2 57.29

Compressor exit vanes losses aptt 0 3

Total diffuser losses(including dumpingloss) Apt

Pt1 .3

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portion of the program Is part of Phase II.

(C) The 'B" diffuser as shown in Figure 11 is a two passage annular

dump diffuser which has been shortened by the addition of

circumferential splitters to accomodate scaling to 4X size

These splitters are located through the compressor exit guide vanes

to provide a maSS air flow division at the plane where the compressor

discharge profile is most uniform. The optimum size and predicted

performance are based upon the specified design parameters In

Table III and Figures 8 and 12.

(C) The "C" diffuser Is a two passage, channeled diffuser and is shown

in rigure 13. This design incorporates compressor exit vanes,

diffuser, and fuel atomitation modules in the shortest possible

axial length. The splitter was added for performance improvement.

This design also permits scaling to I4X size. The diffusion system

consists of four major components. These are 120 compressor exit

vanes, I circumferential splitter, 20 diffuser modules, and 20 fuel

injection modules. As shown in Figure 13, the inlet consists of

belimouth double row vanes to ensure a smooth flow of air. The

circumferential splitter divides the air passage into an upper and

lower flow path. The side walls of the fuel Injection modules serve

as w•lls for the diffuser The airflow is allowed to diffuse in a

mushroom type diffuser and is dumped into a quasi-plenum with a

velocity of 365 ft/see. Both upper and lover diffuser passages are

designed to have the desired rate of diffusion based upon the

analytical studies. The diffuser characteristics are shown in

21

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C~mpe's~o, Fx'fV.,,

Figure 11. Combustion rig "B" diffuser flow path.

22

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iii

i i .Z ... ,,,_iZ5

i a._____, UpperptV_ -- _

V Law er rXL1Vý

I's

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i '4,i .4 .8 1.Z Z. .o

Len~k 0g difu-ser'~~

Figure 12. Diffuser area versus length of "B"-diffuser.

23

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(() Table III

"Bh: Annular two path dump diffuser with circumferential splitter and

inlet vaes

Path 22-r Lower

Ai rflow Wa lb/sea 33.3 30.7

Compressor discharge pressure Pto psia 302.8 30e.8

Diffuser inlet pressure Pt1 psi& 295 293

Diffuser inlet pressure Pal psia 273.9 273.5

Diffuser inlet temperature T1 -R 1460 1460

Diffuser inlet velocity avg. v1 tt/see . 607 584

Diffuser inlet Maich mumber .328 .315

Diffuser inlet width 4R1 in .3275 .3315

Diffuser inlet area Al in2 15.26 14.66

Diffuser length N in 2.0 2.0

Diffuser length to inlet width ratio N/AR 6.1 6.0

Diffuser exit to inlet area ratio AR 1.73 1.8

Diffuser inlet velocity ratio VTax/Vavg 1.1 1.1

Pressure recovery Cp % 43.6 43.5

Diffuser discharge pressure Pt 2 psia 291.3 290.1

Diffuser discharge pressure P.2 Pais 283.1 282.0

Diffuser outlet velocity V2 ft/sec 375 375

Diffuser outlet Mach maber M02 .202 .202

Diffuser outlet area A2 in 2 26.43 26.37

CompressozaeXit vanes losses APt/Pto % 2.65 3.35

Total diffuser losses(includingauMP loss) 4pt/pt. % 2.64 2.4o

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Table IV and Figures 8, 1I, and 15.

(C) The "D" diffuser to also a two pastsage channeled diffuser and is

similar in design principles to "C". The number or fuel injection

modules was increased from 20 to 30 thereby changing the flow Ath

distribution. The four major components of this diffuser version

are 90 compressor exit vanes, 1 circuzferential splitter, 30

diffuser modules, and 30 fuel injeition modules. These fuel

Injection modules have upper and lover diffusing paths as shown

In Figures 16 and 17. The "D" diffuser characteristics are shown

In Table V and Figures 8, 18, and 19.

(C) Diffuser "A" was shown in Figure 7 with no compressor exit guide

vanes in front. Figure 20 shows the "A" diffuser preceded by

guide vanes. The compressor exit guide vanes are shown vith "B"

and "C" diffusers in Figures 11 and 13. Diffuser "D" is shown with

compressor exit guide vanes in Figure 21. These guide vanes have

proven in various combustion rigs to simulate closely the compressor

exit velocity profile found in engines.

(C) The inlet tip and hub diamtters remained the same for the four

diffusers. The *A", "B", snd "*C" diffusers are preceded by 120

compressor exit guide vanes. For the "C" diffuser;, the 120 vanes

match with the use of the 20 fuel Injection modules. ror all

diffusers, approxirhtely 1/6 of the air passes through the fuel

injector modules. For the "A" and "B* diffusers, the refaenina

5/6 of the air is dumped into the plenucs betveen each of the

fuel modules a t is directed into the r-iln combustion ch.nber.

26

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Allison

(C) Table IV

"C": Channeled two path diffuser with circumferential splitter and integratedbell-shaped inlet vanes passages

Diffuser module Fuel inj.module

path Uppe r Lower Uppr Lower

Airflow total Watot #/aec 27.73 2,5.58 5.55 5.12

Airflow per module Wa #/aec 1.3,W 1.279 .2T75 .256o

Compressor discharge press Pto psia -02.8 302.8 302.8 302-8

Diffuser inlet pressure Ptl psia 295 293 295 293

Diffuser inlet pressure Pal paisa 272.8 274.3 282 280

Diffuser inlet temperature Ttl OR 1460 1W60 1460 1460

Diffuser inlet velocity Vl. ft/sec 623 570 486 485

Diffuser inlet Mach number ft ."6 .308 .262 .261

No. Diffuser modules 20 20

No.Fuel atomiz.modules 20 20

Diffuser inlet width Rl In .291 .354

Diffuser length N in 1.5 1.5

Diffuser length to widthratio N/AR,1 5.2 4..3

Diffuser inlet area A inF .622 .624 .155 .14.5

Diffuser inlet velocityratio Vmx/VaVg 1.1 1.1 1.1 1.1

Diffuser discharge press. Pt2 psia 292.3 290.8

Diffuser discharge press. Ps2 psia 284.4 284.2

Diffuser outlet velocity V2 ft/sec 370. 30.

Diffuser out Mach number N2 .199 .18-42

Diffuser outlet area A2 in 1.01 1.01

27

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(W')iT.LE IV (Co,'t)

1 itluser mootae Fuel inj. module

Path Upper Une r Mpe Lower

Difruser outlet to Inletarea ratio AR 3..63 1.62

Pressure recovery y % 2. 4 •.5

Losses through compressorexit vanes &P/Fti % 2.6. 3. 2.65 3.35.

Total losses includin8gdumping per (1) module AP/pt 1 % 2.25 1.87 2.20 2.22

Total annular difr. losses dP/Pt1 1.7

Total annular premixentrance losses AP/Pt1 .4

28

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________________Allisow

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Allison

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.___ __/_ CON 'IDENTIIAL

./o /. 14 1.20o .*• .40. 4 /.o /. /.4 /

Figure 16. Diffuser area versus length of diffuser "D"-dlffuser,

fuel-air spreader module, upper path.

31

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sAlliron

?.30

4,,

"..0 . 40 .8o X6 A1

Figure 17. Diffuser area versus length of diffuser "D"I-dilfuser,

fuel-air spreader module, lower path.

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zp,,~th of ldf~Ocb psFigure 19. Lower path of I'D"-diffuser area versus length of diffuser.

Diffuse,. O wleI -_\ *..'

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Figure 20. Combustion rig "All diffuser flow path.

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In the "C" difftuers these plenums have the shape of small channeled

diffusers. Ibis can be seen in Figure 13. In order to accommodate

the 30 fuel injection modules used with diffuser "D", it was

necessary to reduce the nmber of compressor exit vanes to 90 to

maintain a match between vanes and modules. The use of 90 vanes

results in a better pressure and velocity distribution entering

the passage, in a reduction of frontal areR blockage, and in

an improvement of flow.

Design Criteria and Predicted Performance

(C) The design of' the integrated diffuser-combustor was to have minimum

axial length, which was not to be changed during size ecaling. The

circumferential splitter was incorporated into three of the four

designs to provide a more uniform velocity Trofile and a better

diffuser efficiency, and to permit scaling up to 4X size with no

increase in axial length. Peak diffuser performance is vital in

connection with the fuel injection module concept because a bigher

kinetic energy must be converted into pressure in •}hie portior, of the

system. To assure maximum performance, the following factor must

be incorporated:

* Minimum friction (short length and rapid deceleration)

0 Hinimum boundary layer thickness (short length and slow

deceleration)

0 Retarded separation (slow deceleration)

0 Maximum diffusing (rapid dece ration and long length)

38

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,,__,,,,,, _,,,,, Allison

(M) These factors are contradictory. Therefore the detertiination of

an optimum combination is necessary. The optimum recovery of

these diffusers was investigated and the influence or the velocity

inlet profile on the pressure recovery was considered in this

Investigation. The correlated design curves shown in Figure 6

were chosen to calculate the overall efficiency of these four

diffuser systems. The results are given in the tabulpted

characteristics for each diffuser. From Figure 6, the predicted

performance points of the four diffuser designs are obtained. The

best performance is the "D" diffuser with an inlet to exit area

ratio (AR) of 1.78 and a width to length ratio (N/t3R) of 5.0

for the upper passage and an AR of 1.78 and N/1R of 4.1 lowier

passage.

5. Analysis

(C) One of the important factors In the determining of any diffuser

is the variation of the cross-sectionai area with the path

length. This variation in the passage wiath progresses along a

mean line which is a curved arc lying in an axial plane. See

Figures 13 and 21. To gain some insight into the manner in which

the pressure and velocity might be expected to change along the

length of such a diffuser, calculations were made for two-dimensional

flow. In Figure 22 the ratio of static-to-total-pressure and the

Mach number are plotted against path length for the case where the

inlet Mach number is 0.3. This is for the "A" diffuser. The same

calculations are repeated for the other three diffuser versions,

"D", "C", and "D" and are shown In Figures 23 through 28.

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400

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0.97 -.--/ 00

0

4- on i€, .. If .

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110-

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Len5±hk of diff user "in.

Figure 23. Diffuser parameters versus length of diffuser, "B"31-diffuser, upper path.

41

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Q )'

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400

4~11IDEW JAL

Figure 24. Diffuser parameters versus length of diffuser, "B"-diffuser, lower path.

42

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Allison

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•- . 3z SOO

Y 4.0

S2:

0G .95 -.2oý e s. o

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Figure 25. Diffuser parameters versus length of diffuser, "C"-diffuser. lower path.

43

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,______________________Alison,

.98 ..... - o

d 4 , qV e c l o c +

.5- N 4000E

,94 -. 4.

: CONFIDENTIAL

L e. g-f6 o'f" diffuser ein.

Figure 26. Diffuser parameters versus length of diffuser, "C"I-diffuser, upper path.

44

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N'

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.32 100-__ _

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10 10'

04 .40.

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,, ~Allison,

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f-uel zt:reaer rnodul

-- difr4user module.I.I too

Q .6 .4

ckrdffuse- incul"

L~en ,gtA o d•f~1s~t-e,,e

Figure 28. Diffuser parameters versus length of diffuser, "D"-diffuser, upper path.

46

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S:i •~llison, .

()It is evident from Figure 21 that static pressure rise and Mach

number change the fastest, with respect to distance traveled

by the air, at the entrance to the diffuser. This is typical of

diffusers with linear area distribution ("A" and "B") as shown in,

Figures 22, 23, and 24. It might be stated (Reference 5) that the

pressure rises most rapidly where the air has the greatest

kinetic energy. On the other hand, it might be explained

(Reference 6) that the high velocity and steep gradient just

past the inlet are unfavorable for stable flow conditions and

tend to generate a separation. Accepting the latter hypothesis,

it would be preferable to increase the cross-sectional area more

slowly at the front of tho diffuser end more rapidly at the rear of

the diffuser. Applying this philosophy to an axially symmetric

diffuser converts a straight wall conical diffuser into a be)l

shape. In the three dimensional diffuser the bell shape area

progression is incorporated into the cross-sectional area at an

increasing rate with distance. Diffusers "C" and "D" are this

type.

(C) In the cases of "B", "C", and "D", the diffuser inlet geometry,

mean path, and area ratio remain essentially the same. From

Figures 22, 23 and 24 and Figures 25, 26, 27 and 28, it is seen that

for the first two-thirds of the path length the ci'jss-sectional area of

"C" and "D" is below that of the "A" and "B" design. Then to

47

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Allison _ _ _ _ _ _ _ _ _ _ _

achieve the sawe overall area rntio, the cross-sectlonal area

of 'C* and "D" Increares rapidly in the last quqrter of the

d ifucer.

(C) In looking for a awaos to reduce significantly the length of the

diffuser and to facilitate scaline without going beyond the

shortest length, It was decided a three dimensional channel (tvo

of whose opposing faces diverge while the other opposing converge)

would have the greatest, potential. To get on indication of the

baseline from which the axial length reduction could be nade,

Figure 13.Presents a sketch of a top developed view in the meridional

plane of the three dimensional chaneled diffuser. This geof-try

characterizes the diffuser which Is the basis for the *C" and 'D"

configurations.

(C) Although the conical to undoubtedly the ideal diffuser configuratloo,

It was realized that no com~letely coniel diffuser channels were

possible within the given geot. tric limitations of the "C" and "D"

diffusers. Therefore, a rectangular inlet cross-section could not

be avoided. On this basis, a channel with a constantly chanSing

¢ross-eectional shape was desitewd. This tegins with a rectangular

throat wider in the horizontal direction, then through a gra4dkl

transItIondovnstrePa of the throat,tahes on the slAy of a square,

and finally returns to a rectaigular sh-;e wider in the vertical

direction at the exit location.

48

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,_jllifon

(C) This cross-sectional variation providing a smooth change

in area is based on the following considerations:

* The rate of area change just dotnstream of the rectangular

diffuser inlet was made to follow more closely the optimum

of two-dimensional criteria since its correction was two-

dimensional 4n this region.

* The rate of area change near the exit was selected not to

exc-ed that indicated for optimum of the annular diffuser

(rigure 6).

(C) The resulting exit-to-inlet area ratio remained at the optinrim

for the two-d•iensional configurations. A sector of this diffuser

rig is shown in Figure 21.

(C) The design parameters of the engine diffusers presented in

Tables 11 through V are compared to the work in References (1, 2, 3,

and 4) in Figure 6. The line for velocity ratio equal to 1.0

is taken from Reference (5) and is the line of first appreciable

stall determined vith no Inlet velocity profile. Thi line for

velocity ratio equal to 1.2 is taken from Reference (4) and Reference

(1 and is the line of first appreciable stall with a Jet-ty;e inlet

profi.le and velocity ratio equal to 1.2.

49

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( ON, WDONIiAt

1. General C•,rb•1i•rat t •.

(C) Nveloi-..nt of g-is turbli.- cnrt.us6tion ivtt---s vith-exit t,--.;ort.rec

approa'hing staichic.--tric levels requ're efficter.t o;.-ration

with a high teý,p'ratur-. rise r.:.i a high o',ut lc'd Th. limite

tect d'%ta available In ce:?,uition liter,tiurt, ate a

declining burner effici.ri,:y with Inr.,sir.g ten'-r..ture rite. T.ans

develo,-eent effjrt is bar-,d pri:.•rily on the or•-n.se that ir-ff.-cert

mixing of the air and P,-ýl ahecd of the reaction Zý.-. accounts

for the ef/gciency decline. The solution of this ;rotlern

constitutes a major porticn of this Phase I effort.

(C) Five fuel injection m-l.ules were designed and devele4d. Each

module consists of an air blast system for fuel ato.ization ani

a coebustor dome air inlet systemn to tntroduce and mix the re-vAlning

combusto)r air vith the atz:-ized f',:el. The design of the:e codules

vas based on the follovinZ operp-tional requirercents:

0 Low pressure fuel system

0 Increased nunber of fuel injection points

* Ability to ol-r~te on contaminated fuels

* Premixing of the air ard fuel ahead of the combustor dome.

* High dome air flow

* Smoke free operstion

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Preceding Page Blank

¢OAstN!At

(C) 7ho buriler Sz~s psth it de8tin-d fur 804 oC the air flow 1nj.vcLi,

throuh th,) co•zu.tir do'ne. The other 36.' It utud to COoC the

ao,.ibuator w;%lls th-uough convntlonl film cooling louvre(. T7e

mcobustion air flow distributiun Is:

* Primary air 5O•

* Dilution air 22,A

0 Premix air 12A

* Combustor cooling 4ir 161,,

(C) The purpose or the Fhase I single mr.Aule testing was to develop

and compare the atomization qualities of the various module designs.

The single module test rig is shown on Figure 29 for cold flow

testing and Figure 30 ror hot flow testing. The gas path

simulates the design gas path shown in Figure 1 with the omission of

combustor wall cooling air pass.•es. The rit walls are externally

air cooled to eliminate the effects of cooling film on performance

data. The heat loss through the walls was meosured and taken

into account durin,3 efficiency calculations, 7e. detailed air

flow distribution for the premix combustion syutemo is shown in

Figure 31. The development teating was divided into cold flow

visualization and burning perforr•.nce evaluntion.

(C) The fuel injection modules were designed to the following Phase

II burner sector orating conlition:s:

* Burner inlet temperature 1200"F

* Burner inlet pressure 20 at-t

52

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A~llason

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53v

CON, IDE N V ~

4COft9~# getft jiA

( biurner ross flow 60 Ib/4-c

* Burner temperature rist, 2300YF

(C) The equivalence ratio 0, ac-ual ru,-l-air ra•tio dividcd by the

stoichlomintric fuol-air rotio, wa; &,.,t at. 'iyvu Tnic wtic ai

conpromise between surficient turil'uv rzatlo c.nd a realisic

atomization at twenty itmospheres pressure, 'iL.ure 4 shows the

effects of operatin8 varibie, (burn:r inlet pressure and tem~per-

ature) and design variables (air injection velocity and equivalence

ratio) on mean droplet diameter of the atonized fuel.

(C) The fuel modules were fabricated of plcxiZlass for visual

observation of the mechanisms that effect atomization and droplet

distribution. Water was substituted for fuel as a saf.ety maasure.

Figure 32 shows the physical pro:rtics of kerosýne :6els an!

vater that effect droplet breakup yield comparablc results under

the prevailing test conditions. Strobe liahtinZ techniques were

used to study droplet distribution and estimntion of droplet size.

Collimated lightinG techniques were used to study droplet

distribution and effects of downstream mixinZ on droplet coalescence.

A flow tuft probe was used to map the air flow characteristies of

the dome air entry slots and the recirculation patterns developed

by the modules. A photographic record of the droplet field for

each module was taken for a comparative evaluation. Fig're 33

shows the photographic arranZement. The droplet field was back

lighted with a spark gap strobe light.

54

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I "it jI

-FuelTraversing

inletprobe

Diffuser

wall cooling flow path

Figure 30. Single-module rig-hot amo config=urton.

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Liner cooling (outer)

-Fuez- E

Liner Cooling Doeoon

Description Flow split

Liner coolingOuter wall 0.09Inner wall 0. 07

Dome cooling + dilutionOuter 0.13Inner 0. 09

Premix 0. 12Primary + dilution 0.50

Total 1.00

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Figure 31. Airflow split in premix combustion systems.

57

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Afllimon

sAtomýFatebn, ve/ccctv .R9o ftlsec,

Q)

0 so /00 /50 200Temperatu re of leu' ~-O

Figure 32. Mean droplet diameter versus temperature for fuel and water.

55

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CONFODENTIAL

(C) The plexiglass configurations were phased into metal modules

for evaluation or the atomisation, vaporization, and mixing

potential or the injector designs under burning conditions.

"Three dimensional temperature traverces were recorded with radial

triversing probe.. A sample isotherm temperature plot is shown In

Figure 3-. The temporature traverses were checked with chroma-

topraph samples taken through the same radial traversing probes.

Booke samples wore taken at the exit plane through ,he same probes

a•d recorded using Bnchirach spot samplin3 techniques. The overall

pressure drop var, recorded as module inlet total pressure minus

the burner outlet total pressure.

2. Vee Outter Module

(C) The vee gutter module shown in Figure 35 Is sized to have 20

motulea per annular combustion liner. This module design conbinos

fuel-air premix and high dome air flow with the vee gutter

recirculation developed for afterburner systems. The vee gutter

concept was not used in the circumferential plane of the afterburner

• ~but was developed In the radial plane" to:

* Optimize the recirculation pattern of the high aspect ratio

slot to mix the primary-dilution air with the fuel-air

premix flow

* Achieve modular linearity for developmemnt changes in liner

height

0 Allow independent removal of the oomponents of the fuel

distribution system

60

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4104

61-

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__________________________________ _________________________________

aI

62ICONFIENTIA

CO NF IDE NT IA,

Allison

(a) In the vse gutter module the fuel is atomized by air at a

velocity ot 304 ft/seo floving across the atomizLng surface. The

mixture, designed for an equivalence ratio of five , flows

through the six slots into the recirculation zone. The remainingW

air flow Is Injeotod through the high aspect ratio radial slcts

between modules. Th,, yes gutter fuel distribution tube Vas

designed to match a fuel injection jet to each injection slot,

There are 6 Injection points for each module and 120 for a full

annular combustor.

(C) The atomization of the fuel from this module Is of a nature to

create the existence of a wide distribution of fuel droplet sizes.

The distribution is made mechanically using a large number of

Injection points. The flow quality at the design point prem'.x

equivalence ratio of five and the premix velocity of 304 ft/sec

is shown in Figure 36. Supports have been added to this piotured

model for rigidity to enable the flow study of the air both inside

and outside of the vee.

3. Swixl Chamber Module

(C) The swirl chamber module shown in Figure S 1. '2i4 ft e reVIe 30

modules per annular liner. Each module eomer!W. at me veex

chamber and one fuel injection point. Visal tUdites, R*ftrence (8),

indicates a boundary layer exists on the end wall of the conventional

vortex chamber which does not become part of the vortex flow. To recover

this lost volume, the swirl chamber module has the vortex energized

by air emission through two swirl vanes located through the vortex

63

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chamber ecd wall. The use of the boundary layer arcu to drive the

vortex results in a more efficient use or the chauber axial

length. The eo~e flow visunlization studles, R~fercene (8), also

predict optimum mixinj occurs with the fuel injection In a

radial plane. This module has fuel Injection in a radial plane.

Primary air is introduced through high aspect ratio slots located

in the module cone. The dilution air entry Is through radial slots

between fuel modules.

(C) Flow conditions inside the swirl chnraber and in the module cone

were evaluated using water in air. The spray quality at maximum

water flow conditions and 304 ft/sec ambient air flow Is shown in

Figure 38. Spray quality was not affected by a change in simulated

equivalence ratio and was changed verý" slightly by a change in

velocity above 304 ft/sec. The circulation from the cone slots

surrounding the swirl chamber was altered durin3 the water and air

flow testing. The testing of the altered module confirmed both

the high degree of mixing within the module cone and a well este.blished

circulation for primary zone reaction. This single point injection

module was designed to demonstrate a higher degree of primary

atomization than In the vee gutter without the coverage by

numerous jets.

1 . Conical Fuel-Air Spreader Module

(C) The conical fuel-air spreader module, Figure 39, is sized for a

_ O D66

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single row fuel distribution or 30 modules per annular conbustor.

This module has a radial fuel entry to the inner air mixing chamber.

This chamber performs the dual function of providing fuel-air

mixing and even distribution around, the exit cone. Atomization

occurs at the exit of the inner mixing chamber. The atomized fuel

is surrounded and carried to the reaction zone by prlmary air

through the inner and outer chamber passages. This is shown in

Figure 1.0 where mixing air is on both sides of the atomized fuel.

This type of fuel addition s'hould give the finest fuel spray since

coalescence Is prevented and the droplets held in suspension by

surrounding the atomized fuel with air. The distribution from this

model shows a wide dispersion of drops resulting from the smaller

droplet size.

9 . Double Reversal Chute Module

(0) the double reversal chute module shown in Figure 41 Is sized for 20

modules per liner. Each module has four fuel distribution points.

The fuel-air premix chute encloses the fuel metering nozzles and the

fuel atomizing surface. From this chute, the atomized mixture enters

an enclosed primary mixing zone for mixing and dilution vith the

primary airflow. This mixture enters the combustion zone for burning.

The remaining dilution air Is ducted In four chutes adjacent to the

V,,*m chutes. The flow channel for air to each area of the do4e has

been constructed as a separs.te duct. This was accomplished in an

effort to get the effect of direct placement of primary air and dilution

air*

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V COWM4AN~AD PALS SOT?

(0) The basic test system for testing contaminated fuels vith premix

miodules Is shown on FiVgre •1. Ihis system oomprixes three

e9ements. A motor driven bel$t driven at a regulated speed carries

regulated qiuantities of contaminant for dumping into the fuel.

supply. A dual piping system has been &ied to retain the

oomtasiuats in Suspenslio. A vam e U p mp sad the necessary

regulating valves se uwed a o ee"wal te uel flow.

C) TUhe fue used wa 31t1.)- i I m' a ot,,M'4 ted per Nil-Z.5007.

beh nodule ve tWSW&i 9We As- o Ah fuai ,g cyoles

• mi• mn fAwl f3lw i

0 Awre -l • 4 |

0 zero tuel.flw 3

(a) Fuel flow versus Pressure drop wore reorded before ad after the

test using elesa tel. ariag the rmIt with contaminated fuel,

a flow check was zs~e at eme~zalf hour Intervals.

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VZ FUEL IN,•b•CTON COMPUTMHI PFROORAM

(q) The fuel injection computer program is modeled on 6 fuel Injection

system which depends upon \•el atomiz1tionP vaporilzatlon and

the mIxing of fuel a&n primrry air as functions of:

* Pftqmx air Injeetion velocity, pressure and temperature

* FU, velocity wAd tsperature

* 71.sie0 ".r .. iee of the fuel

* Xuotor os• •*nLae es relative to the air stream

* Combstor pk• @er 4iewnsions

(C) The formulation of the P"eii •inei7 equations for atomization and

vaporIzation was base" on the work in Reference (7). The theoretical

model vwil be correlaUd with the date from Phase I single module

testing. The three dimensional arrays of temperature an! ebroma-

tograph e&.-veys vlil be correlated with the reaction rate para-toer.

The reaction rate parameter correlated tUe burner efficiency with

the burner operating variables. The level of burner efficiency

wIll then be related to the overall eftets of atomisation,

vaporization, and mixing as a function of the operating variables.

(C) The correlation of the predicted model performance to actual test

performanoe vill continue through Phase I1 and Phase III testing.

The fuel Injector portion of the computer program is a part of a more

extensive computer program which will result in computerized

predictions. These predictions rill be the fuel droplet size,

evaporation rate, and mixing potential of air atomized fuel systems

over the operating ranges described by the four Air Force mission

requirements.

(0) The Preliminary computer program dealing with fuel properties

and nixing was used to generate the data shorn in Figure 4•.

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V11 TOT! IRUII

1. inrgle WWIu.l.e urnifh TWsts

(M) Me prposes of the burning section of Phase I testing on the single module

rig were:

0 Develop the particular premix system of each module

* Compare the effectiveness or the various premix designs

* Obtain correlation data for the computer prediction program

that models the atomization, vaporisation end mixing regime

of the high dome flow cambustor.

Data Acquisition

(C) We modules wore tested at three fuel-air ratios over two operating conditions.

Imet Total Pressure in. vA. 60 15_Wret Total Teeratre Ftr ' .,

Do 300 300.

2we auimum burner e"it temperature was limited to 3200*7 to maintain a

reasonable life on the thermocouples and obromatograph sanpling probes. 20

three operating fuel-air ratios were selected- o give the widest range sad

still have stable rig conditions. This range is desirable for the method used

to calculate module design fuel-air ratios*.

*M~odule design fuel-air ratio is the ratio at which the burner efficiencyderived from gSs chromatograph analysis vas a maximum.

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Oservationsa& M Comparisons of Mdules

(a) able VIT is a OUMrMM o the observatioms ad omarisons of the five modules.

Ue double reversal aoate m-dwle has been oiLnmated farm furtr considaration.

lug 4060e is too 1mited Go trum W"oIng stabiity and, ooeeoquemtl, would

not eutaln below a ftel-air (?/A) of 0.018. be dilution oaites gave good

dilution nmixi•. lowever, the design of %he premax chutes d44 not provide

enough realroulatioa to promte a baek mix combustion &om.

PmLx Euivalence Ratio

(0) A premix equivalence ratio of five wsa the Initial design point for the modules.

At the design point the overail F/A ratio is 0.0418 and 32.5% of the air flow

is required for proper fuel-air premix. During initial bardware development

a rang of equivalence ratios were toested. This testing was done prior to

flow coeffioient definition for the various air flow passages. Ube e gutter

module stability was increased with increasing equivalence ratio. ZXoreasing

the equivalence ratio above five results in a lower Ael air designs thus, a

lover lean blowout F/A ratio. Although the lean blowout charmoteristics wer

desirable, 4evelopment will be directed toward increasing the design ?/A ratio

to maintain combustion efficiency during high temperature rise operations.

Pressure Drop

(C) Tbe single modele rig simuates the inlet flow to the module from a dump

diffuser at an exit velocity of W0 feet per second. Mhe total pressure drop

across the module, between module inlet and burner exit, is shown in Figure 52.

Burner Efficiency

(C) The burner efficiency was calculated from gas chromatograph sampling at three

exial stationa. Figure 53 shows chromatograpr efficiency " a function of

overall fuel-air ratio (FAD). e efficiency of the We gutter falls off

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*iee Sutterin sarl chamer

Qb A PvI spr.eader

.05 aoo&•ble re~eee$Sa chut 'e•_ .

.02.

cold flw

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Figure 52. Pressure drop versus Mach number under cold and burning conditions.

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Fi71gure 53. Chromatograph efficiency versus fuel-air ratio at 2 and 5 atmospheres.

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Burner Ifficiency (coant.)

(C) rapidly above a FAO of 0,017, which coincides with the design fuel-air ratio.

(C) This problem is unique to the We gutter module. A postulation to increase

the design fuel-air ratio by staging the fuel will be evaluated in Phase 11

sector testing. Fuel will be injected Into the bypass dilution air into a

secondary recirculation tons located downstream from the primary and strongest

recirculation zone. The recirculation zones were defined on the sixty degree

diffuser sector rig flowing water. The venturi-vortex module has a wide angle

fuel spray cone. This resulted in combustion on the rig sector walls which

distorts the performance evaluation. Improved mixing occurred an fuel-air

ratio increased. This Is best demonstrated with Figure 53 which shows

increasing efficiency with Increasing fuel-air ratio over the range tested.

(C) The sirl chamer and fuel-air spreader modules have higher design fuel-air

ratios.

(C) Verification of the level of impoitance of the design fuel-air ratio is shown

in Figure 54 Figure 514 also shows the isotherm and zone efficiency profiles

at the burner sector maan radial depth at two overall fuel-ar ratios.

(C) At the operating condition below the design fuel-air ratio of .017 the reaction

soew is attached to the Vee gutter, resulting in adequate completion of the

reaction at an L/E of 1.75. Increasing the fuel-air ratio above,.0l7 results

in a blow-off of the reaction zone downstream with insufficient tim to

omplete the reaction.

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Burner Ifficiemay (cost.)

(C) TMe cparisonC of overall combuotion and the effectivenwess of dilution mixing

air to shown with Figure 55. lbs various modules have different air masso flow

rates which result In different beat loadings. The usual !IAm .2se

parameter has been divided by beat load instead or temperature rise in an

attempt to normalize the modules for comparative purposes.

Blowoutsa

MC The fuel-air ratio at lean blowout of the various nodules is approximatelyo=e-third the design fuel-air ratio. This ratio may change during sector

testing, but the results indicate that high, temperature rise whioaue will

have correspondingly high blowouts..

(Q) 9e blowout points an shown on Fiur

(C) b~hmaat ga"s mak samples were taken at each operating condition. There was

no trace of mke generation from amy of the modules tested. Static tube

sampling probes were used with spot verificationi samples taken with an is*-

kinetic probe.

2. Contaminated ftel

(0) Ihree types of fuel Inlet devices Vero Investigated for flowing contaminated

fuel to the JaL I 5OOT2 specification. Three units were made from 310

stainless and one unit was made from 347 stainless. Of these devices. three

orifices were constructed with thaicknss equal to two times the diameter.

The other orifice had the thickness equal to the diameter. Orifice sizes of

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rigure 55. pattern factor versxs overall fuel-air ratio at 2 and 5 atmosph~eres.

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FlIFw 56. Inlet Pregeue vrwsus fuel-ai ratio at lean blowout.

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Contaminated Fuel (coant.)

(M) .W02 - ,OD were flowed. 8hae ot the orifice showed Indioation of cloging.

The material had LnAications of erosion and, therefore, the .moseaLty .,, iaog

wear resistant material was experienced. Figure 57 shows flow comparisons

before and &uter contaminated fuel testing.

3. 1Low Visuli•a3iation Rigs

(C) Yn this section io presented diffuser performanoe ata - inlet and outlet

velocity profiles - masured for the "A" sad "B" diffuser rig models. 2Mis

data in compared with predicted performance date. Tist data obtained

correlated closely to the theoretical predicted performance characteristios.

Soe flow visualization photographs of "A" diffuser-combustor an shown in

Fiure 58. Type "A" diffuser Is the surge passage, straight dump annular

diffuser. Type "B" diffuser is the two passage annular dump with a circum-

ferential splitter. The diffuser inlet geometry at the trai2ing edge of the

turning vanes remained similsr for both types of diffusers tested. Table DX

is a sumar of significant design and tes t data for the "A" and "B" diffusers.

Test Configuration

(0) A cross sectional view of the diffuser test rig for testing both diffusers

is shown in Figure 59. The geometry of the test rig differs slightly.

The inlet of the "A" diffuser has a smooth, fist velocity proflme. The "3"

type diffuser inlet has integrated turning vanes to generate an inlet velocity

profile.

(C) The diffuser inlet instrumentation was located in a plane of the throat

one quarter inch downstream of the exit vane trailing edge. Pressures were

observed on water manometers. The diffuser discharge Instrumentation was

mounted similar to the inlet configration.

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4k.4,s, ,4tarbdA 94,. C4,U 7F'd

qe,

ALleurA•ADD Joee Wi oe "

orw~c/ f/o,.. lot Iba.lhf.

Figure 57. Flow before and a.fter contaminated fuel teottng,

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Single path 7 1 2 deg- diffuser

Single path 7 1,2 deg diffuser dump area

Figure 58. Flow tracers showhng flow through "A" diffuser and into premix area.

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mea~ts sa" Discussios

(0) In purpose of this section to to present a summar of results ot an experi-

montail Investigation ia vwic parametri studies yore performd using rig

sod•A of the "A" and W" type diffusere.

(0) Diuoser presmare recovery (0p) at the inlet Mbh numbers from 0.1 to 0.35

ean presented f "A"' ad "3" difftuers. Typical diffuser velocity profiles

an preseae fer both diffusers at several Islet conditions. The Mob

aumber betwoeem the diffuser Inlet an4 exit stations follow closely the predicted

premi•e recovery and diffuser losses.

Diffuser ffiTieney, (pressure recovery) "A" Diffuser

(0) Tests on this ecnfiguration revealed a asight diffuser efficiency (pressure

recovery) increase with an increasing ebh number. The performae of this

4iffuser Van encouraging. Calculations using the test data revealed an average

diffuser pressure recovery of C•p 63.5% hich is essentially constant for

selected M•bh numbers (0.1 to 0.35). This is an excellent pressure recovery

for this type of diffuser and is three to four and aon halr pernent higher

than the predicted pressure recovery for the original design (see Table SK).

Velocity Profile "A" Diffuser

(a) The inlet velocity was essentially uniform over the sn .ulus height at all inLO

co•d•ticas investi&t•ed. •ther was no flow seponition indicated by the near

norml turbulent velocity profiles at the diffuser exit plane for any of the

inlet conditions tested. The exit velocity profiles increased as the divergence -

angle was increased.

(C) The total system losns and diffuser inlet-exit pressure drop are shown

in Figure 60.

(C) A coemprison of velocity profiles at the diffuser inlet and exit for I•let

Mach numbers 0.18 to 0.30 are shown In Pigures 61 and 62.

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Results and Discussion (oant.)

BI" Type Diffuser

(C) The objective of the "B" diffuser testing was to determine the effect of a

circumferential splitter on diffuser performance. The splitter was located

on the centerbody of on annular sector of a subsonic diffuser.

Diffuser Pressure Recovery " Diffuser

(C) Different inlet Mach number conditions produced alight changes In the pressure

recovery characteristics in both the upper and lower passage@. The upper

passage showed a pressure recovery so' Cp v 5/,, Versus C. - 45.6% predicted

recovery. The lover passage pressure recovery was Cp a t4 % s Opposed

to a predicted C. =43.5%. This pbenomnar of change in the total pressure

levels is explained In the velocity profile discussion.

(C) Comparisons of predicted and actual performance data for the "B" diffuser

Inlet and exit are shown in Table Ix . The test data exhibits very close

agreement to predicted performance points.

Velocity Profile- "B" Diffuser

"(C) The velocity profiles for the diffuser inlet and exit are shown in Figures

63, 64 , 65, and 66. The velocity profile did not exhibit general amplifi-

cation characteristics as diffusion was increased.

(C) It is felt that the Vee gutter module acted as a floe restriction and had a

tendency to prevent profile amplification. This lack of velocity profi.e

amplification results in a thinner boundary layer buildup and, consequently,

an improvement in pressure recovery (see Table IX').

101

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Figure 60. "A diffuser pressur* losses and dump losses versus Mach nmuber.

102

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(C) There was no tfov separation indioste by the near flat, turbulent veJocity

profiles at the difuser exit pl.as for my oa the iolet conditions tested.

(C) The perToruance of this diftuser was good. This gives enaooureasent to use

ot this type oft dituser for scaling purposes,

(C) The total pressure losses of the system and diffeer inl•et-exit Pressure

drop versus 1ch nuaber ate shown in Figure 67

a,,

4.

.e .h WI6.•

Figure 67. "B" diffuser pressure losses and dump losses versus Mach number.

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V' NT PHASE I I PflOORAI

(C) Phase 1 will be the continued evaluation of short Integrated

diffuser* and pre-mix modfiles. The scope of these evaluations will

be Increased by combining both the diffuser and premix systems. Zn

addition the combined diffuser and premix viii be evaluated with a

combustion volume equal to or less than that required for pressure

atomization. The combustor volunw, therefore, will remain flexible

during this testing. The cooling of the combustor walls will be

explored and defined for the performance testing of Phase III.

(C) The major effort of Phase Ui will be accomplished using a 60'

sector of the flow path of an annular combustor system. Various

configurations of diffuser$, premix injectors, and combustors will

also be used to indicate the system variability with optimization

of components, while operating at pressures up to 20 atmospheres

and inlet temperatures in excess of 000F. The injector computer

program initiated in Phase I will be refined and a diffuser

computer program initiated.

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1X REPFERENCE:S

1. Carlson, J. J., and Johnston, J. P., Effects of Wall Shape onFlow Re•i•es and Performance in Strai. ht' jjo Oi-i-m•n 7ni-•ni-D'fucers

2. Waltman, B. A., Reneau, L. R., and Kline, S. J., "Effects of InletConditions on Performance of Two-Dimencional Diffusers" (U) Journalof Basic Engineering, Transactions ASME, Series D, Vol. 83, 1961

3. Kline, S. J., Abbott, D. E., and Fox, R. W., "Optimum Design ofStraight-Walled Diffusers" (U) Journal of Basic Engineering,Transactions ASME, Seriet D, Vol. 81, 1959

4. Sovran, G., and Klomp, E. D., ExMyimentally Determined OptimumOeometries for Rectilinear Ditrser wit-h Rccota-un-r.al_

orAnuarCos-eciiFUT eerlMotor. Research Puiblication,G0M-511, Tovenber,l963

5. Reneau, L. R., Johnston, J. P., and Kline, S. J., Performance and 6LDesln of StraithtTwo-Dimensional Diff'users (U), Stanford UniversityPress, P?-dSeptembTi-r, 49u

6. Henderson, F. D., Effect of Profile and Length on Efficiency ofRDiffusers (U), i-"•1e--- Propulsion Esablshmnt, T•ch •-'?ote

No. 181, September, 1959

7. Longwell. J. P., "Combustion of Liquid Fuels" (U), High Speed Aero-dynamics and Jet Propulsion, Vol. II, Combustion Processes, PrincetonUniversity Press, 1956

8. Roschke, E. J., Flow Visualization Studies of a Confined, Jet-DrivenWater Vortex (U)7 -pul'ion'•-6rato--j, " 3-l"•l0,"pter

9. Flow of Fluids Throuj..alves, Fittings, and Pipes (U), Engineert•n

~~~irnen, Crne Cupan71~ehzi~a Ppe-r W*o. iii, 1957I

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X BIBLIOGRAPHY

Carlson, J. J. and Johnston, J. P., Effects of Wall Shape on FlowR~eImes and Performance In Stral ht Two-Dirnns-owil Diffu-ers-(u)Stanford U-niversi1ty, -PD. l, J-uno 1965--

Clark, B. J., Breakug.of a Liquid Jet In a Transveree Flow of Gas (U),Lewis Research Centeri,

Cocanower, A. B., Kline, S. J., and Johnston, J. P., A UnifiedMethod for Predictin$ the Performance of Subconic Diffuoars of

everal Gro•etries (U), St fo University, PD-lOA, y i9-5

Fernholz, Von H., "The Theoretical Boundary Layer Investigation forOptimum Design of Sub-Sonic Diffusers" (U) Ingeniour Archiv X)OCVBand 1966

Kline, S. J., Abbott, D. E., and Fox, R. W., "Optimum Design ofStraight-Walled Diffusers" (U), Journal of Basic Engineering,Transactions ASME, Series D, Vol. 81, 1959

Longwell, J. P., and Weiss, M. A., "Mixing and Distribution ofLiquids in High Velocity Air Streams" (U), Industrial and EngineeringChemistry Journal, March 1953

Longvell, J. P., "Combustion of Liquid Fuels" (U), High SpeedAerodynamics and Jet Propulsion, Vol. II, Combustion Processes,Princeton University Press, 1956

Lyshevskly, A. S., The Coefficient of Free Turbulence in a Jet ofAtomized Liquid Fuel (U), NASA V' F-351 Aprril1965

Mugele, R. A., and Evans, H. D., "Droplet Size Distribution In Sprays"(U), Industrial and Engineering Chemistry Journal, June 1951

Nicholls, J. A., Debora, E. K., and Raglund, K. W., A Stud. of TwoPhase Detonation as It Relates to Rocket Motor Combustion Instability

~UJ NAA R-272, August, 1965

115

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Priems R. J. and Heldzman, N. F., "Vaporization of Propellants inRocket, ggines" (U), American Rocket Society Journal, November 1959

Putnams A. A. et al, Injection and Combustion oa Liqj,.d Fuels (U),Battelle Memorial Institute, W1DT5Cf 7.GAzRe hl 195-7"

Popov, Mintcho, Model Ex2eriments on Atomization of Liqu•ds (U),NASA, TT' r-65, July 196

fRoschke, E. J., Experimental Investigation of a Confined, Jet-Driven

Water Vortex (U),--t P-opulsion Laborato-ry o. 32--92, October

Roschke, E. J., Flow Visualization Studies of a Confined, Jet-DrivenWater Vortex (U), Jet Propulsion Laboratory, TR No. 32-1004, September

Schuyler, F. L., Combustion Instability: Liquid Stream and DropletBehvior (U), WADC 7R 59-720, September 1960

Sitkei, Gyorg, Contribution to the Theory of Jet Atomization (U),NASA TT F-129, October 1963

Waitman, B. A., Reneau, L. R., and Kline, S. J., "Effects of InletConditions on Performance of Two-Dimeasional Diffusers" (U), Journalof Basle Engineering, Transactions ASME, Series D, Vol. 83, 1961

116

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CONFIDPNTIAL _

Security ClassiflcationDOCUMENT CONTROL DATA. R&D

(Iecuriyv clseallied ti•i ofl lilI., budy of abatract and rndueems annotatoun mues be entered v*en the overall eIIporte 4 clea•i•ied)

I ORIGINATING ACTIVITY (C•puE.. author) . . .. da B.• e a IIT C A•..I.,.I€roN

Allison Division of General Motors I Io ene ai dA tac ins restricted data

Indianapolis, Indiana 46206 ab GROUP

"3 REPORT TITLE EXPLORATORY DEVELOPMIE'NT OF RI;I)UCED I,ENGT11 TURBO-PROPULSION COMBUSTION SYSTEMS. PART I-PRI{LIMINARY COMPONENTDESIGN AND DEVELOPMENT

"4. DESCRIPTIVE NOTES (Typs of repotE and Inclueive daeit)

Phase I final report for the period 1 July 1967 through 31 December 1967S AUTHOR(S) (Lose name. ftirs name, Initial)

Simon, Jack J. Wyrobek, J. T.Stettler, Richard J.MacNaughton. Donald A.

G. REPO T DY ATE 7 TOAL.NO. OF PAgO ` 7 .NO OFR S

'n.O....August 1968 1"°"° "" I" '"117 9

go, CONTRACT OR GRANT NO. 00 ORIRINATSe RKPORT NUMUsiR(S)

F33615-67-C-1939 EDR 5610A PROJSCT NO.

3066C. Ob. ATN ER Rs PORT NO(S) (Any' otha.numhipeu e damay be aeolbnoE

Task No. 306603 leporj

d. AFAPL-TR-68-810. A V A IL AWLITYr/MITATION NOTICES

II. SUPPLEMENTARY NOTES Design, test, and 11. SPONSORING MILITARY ACTIVITy

results of venturi-vortex fuel module Air Force Aero Propulsion Laboratoryconcept to be restricted to govern- Air Force Systems commandment agencies Wright-Patterson Air Force BasementageniesOhio 45433

IS. ABSTRACT

Advanced design turbo-propulsion engines for future aircraft require a compact,high performance combustion system for high thrust-to-weight ratios and anincreased level of reliability. To attain this goal, two concepts based on maxi-mum combustor dome airflow are being developed. The first is an integration

of the diffuser and combustor to achieve minimum length and maximum effi-

ciency with smoke free operation. The second is to achieve improved fuel in-

jection using a high density premix fuel injection technique to obtain acceptable

exit temperature patterns in a high temperature rise combustor. The fuel in-

jection technique is the development of single modules for premixing of low

pressure fuel and high density air ahead of the combustor dome. These modules

are capable of accepting contaminated fuels and can be combined to permit test-

ing as sectors of a full annular combustor. (U)

Initial testing of the various fuel injection premix modules and different designs

of the integrated diffuser-combustor under Phase I of this program has verified -

the soundness of the concepts being developed. Based upon these results, the

most promising premix modules and the best diffuser-combustor design will

be combined as sectors of a full annular combustor for further evaluation. (U)

(Distribution of this abstract is unlimited.)

SDD ,l-pN'". 1473 CONFIDENTIALSocurity Classification

CONFLDENTIALSecurity Classification -__

14 LINK A LINK 6 LINK C

MOLE WT ROtCLI WT MOLE WY

Annular Combustor

Premix fuel modulesInte grated diffuser -combus torCombustor high dome flowFuel injection techniquesFuel-air mixingHigh temperature riseExit temperature profileContaminated fuelSmoke free operation

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