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“-““ “%/
NATIONAL ADVISORY COMMITTEEFOR AERONAUTICS
dlL 311947
TECHNICAL NOTE
No. 1374
6
EXPERIMENTAL STUDIES OF THE KNOCK-LIMITED BLENDING
CHARACTERISTICS OF AVIATION FUEU3
II - INVES’IXGATION OF LEADED PARAFFINIC FUEIS
IN AN AIR-COOLED CYLINDER
By Jerrold D. Wear and Newell D. Sanders
.-
9
Flight Propulsion Research LaboratoryCleveland, Ohio
WashingtonJuly 1947
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‘i~illBimEilii[~31176014258454
1.— ~_ _,_ —.-~... r
NATIONAL AIYKL50RY
EXPERIMENTAL STuTnE3
COMMiTTEE FOR AERONAUTICS
gm 1374.
OF THE KNOCK-LIMITED
CHARACTERISTICS OF A~ATION FUELS”
II - HWISTIGATION OF LEADED PARAFFINIC!
IN AN AIR-COOLED CYLINDER
BLENDING
By Jerrold D. Wear and Newell D. Sanders
SUNMARY
The relation between knock limit and blend comp.oeition ofselected aviation fuel components Individually blended withvirgfn base and with alkylate wae determined in a full-scaleair-cooled aircre.Tt-+n@ne cylinder: In addition the”follow-ing correlations were examined:
(a] The knock-lhited performance of a full-scale engine atlean-mixture operation plotted against the knock-limited perform-ance of the engine at rich-mixture operation for a series offuels
(b) The knock-llmited performance of a full-scale engine atrich-mixture operation plotted’against the Lmmck-llmited perform-ance at rich-mixture operation of a small-scale engtne for aseries of fuels
In each case the following methods of specifying the knock-limited performance of the engine were Investigated:
(1) Knock.-limited,indicatedmean effective prossure
(2) Percentage of S-4 plus 4 rGlTEL per gallon in M-4 plus4 ml TEL p~r gallon’to giv6””anequal knock-limited indicated meaneffective pressure
.
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(3) Ratio of indicated mean effective pressure of test fuelto indicated mean effective pressure of clear S-4 reference fuel,all other conditions being the same.
2
tive
NACATN NO. ?-374
Results indicated that the knock-limited indicated mean effec--pree~~es of’the ij~~affinicfuels inveat}gated, except the
neohexane blends at “lean&it~”60 for a ti~tiktiv+~e 61-200 B,T.C.,followed the reciprocal blending equation provided ”thatthe temper-ature of the cylinder walls near the knocking zone was held con-19tant. .-,
Percentage of S-4 referenGe fuel irLM-4 reference fuel (bothfuels containing 4 ml TEL/gal) for au equal knock-liml.tedindicatedmean effective pressure of the pareffinic fuels te&ted at a sparkadvance of’20° B.T.C. Bave ratings of the parafflnic fuels thatwere independent of the type of engine used in these teats and ofthe fuel-ah ratio,
INTRODUCTION
An investigation of the bock-limited blendingties of aviation-fuel components ie be~ng con@ct@Cleveland laborato~ tu determine the extent of the
characters -at the NACAapplicability
of the reciprocal biendiu relation developed in r~erence ~“This relati& is a8 follo%:
where
imep
(imep)l, (tiep)2, (tiep)~ f . ●
The results of hblends of a 62-octaneand blends of S and
preltiinarx
N3
‘m+ “ “ “
knock-limited Indicated meaneffective pressure &the fuelblend
knock-limited indicated meaneffective pressures of compo-nents 1, 2, 3, . . ., respec-t~vely, when Individuallytested
mass fractions of components 1,2, 3, . , ,, respectively, inthe fuel blend
investigation (reference 2) withparaffinic gasaline and an ayiation alblateM reference fuels indicated that the
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NACA TN No- 1374 3
reciprocal blendh.g relation derlve~ in reference 1 is applicableto blends of paraffinic fuels at rich mixtures, On the other hand,the relation weA not applicable to lean-mixture data for paraf-flnic fuels and is prGbahb that the dise@eement may haveresulted from improper control Qf cylinder temperatures adjacentto the knocktng zone.
The primary purpose of the investigation reported is tostudy the blending characteristics of a number of leaded paraf-finic aviation-fuel components in a full-scale air-cooled enginecylinder. A secondary purpose is to compare the following cor-relations:
(a) The knock-limited performance of a full-scale engine atlean-mixture operation plotted against the knock-limited perform-ance of the engine at rich-mixture operation for a series of ~fuels
(b) The knock-llmited performance of a full-scale engine atrich-mixture operation plotted agafnst the knock-ltiited perfomn-ance at rich-mixture operation of a small-scale engine for aseries of fuels
In each case the following methods of specifying the knock-limitedperformance of the engine were investigated:
(1) ~ock-ltitted indicated mean effective pressure
(2) Percentage of S-4 plus 4ml TEL per gallon inM-4 plus4 ml TEL per Qallon to give an equal knock-ltiited indicated meaneffective pressure
(3) Ratio of indicated mean effective pressure of test fuelto indicated mean effective pressure of clear S-4 reference fuel,all other
Runsings were
conditions being-the same
were made on a full-scale air-cooled cylinder; F-4 rat-determined for most of the blends.
The basevirgin base.
fuels used in this investigation were alkylate andThe blending components were:
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.
-NACATN No. 1374
T~iptane (2,2,3-trimethylbutane)Hot-acid octaneIsopentane (2-methylbutane)Diisopropyl (2,3-dimethylbutane)Neohexane (2,2-dhnethylbutane)
.
.
The base fuels a~d all blending components contained 4 ml TIZ pergallon.
Triptane, hot-acid octane, Isopentane, diisopropyl, andneohexane were individually blended with a virgin base stock andtested at spark advances of 20° qnd 30° B.T.C. Tr$ptane Wd ho.t-acid octane were blended with alkylate and tested at a sparkadvance of 20° B.T.C.
The following reference fuels were also investigated at theseengine conditions to obtain the reference-fuel fremework:
.s-4S-4 plus 4 ml TEL per gallon’50-pereent S-4 and 50-percent M-4 bothleaded to 4 ml TEL per gallon
The triptane was supplied by the General Motors Corporation.
APPARATUS ANDTROCEIURE
An investigationwas conducted with an R-2800 cylindermounted on a CUE crankcase. The apparatus was the seineasdescribed in detail in reference 2, with the addition o~a thermo-couple embedded in the cylinder head about one-sixteenth inch fromthe combustion-chemberwall at the exhaust end zone (fig. 1). Theknocking zone was aemuned to coincide with the exhaust end zone.An automatic temperature regulator was attached to this th+mmo-couple a@ controlled the cooling-ajr flow to maintain the temper-ature constant at the thermocouple,
The engine was operated at the following conditio~, whichwere changed from the conditions in reference 2 to permit agreater percentage of triptane in base fuel to be tested:
.
NACA TN No. 1374 5
Compression ratio . . . . . . . . . . . . . . . . . . . . ...7.7Spark advance, deg Bm.T.C. .m. . . ... . . . .“. . . . . .20and30Engine speed~rpm . . . . . . .. . .. . . . . . . . . . ,. .2000Condition of fuel-air mixture . . , . . . . . . . . . PrevaporizedInlet-mixture temperature, OF . . . . . , . . . . . . . . . . . 240Cooling-air temperature, %!’. . , . . . . , . , . . . . 100 to 110Cylinder-head temperature at efiaust end zone, % . . . . . . . 350
T!aetemperature of the rear spark-plug bushing varted from 375° to425° F. . . .
The test procedure was the came as the procedure described inreference 2. e
RESULTS AND DISCUSSION
Mixture-response curves. - The mixture-response curves forthe reference fuels (S-4 and 50-percent S-4 plus 50-percent M-4),base fuels, and blends of base fuels and blending agents are showin figure 2. The blends of @se fuels and blending agents showncontain the maxtirm concentration’of blending agents tested inthis investigation. Complete mixture-response curves were notobtained for blends of lower concentration.
The hmock-limited perfonmnce of vsrious blends of base fuelswith blending components at fuel-air ratios of 0.067 and 0.10 issummarized in table I. The perfozmmnce values are given in termsof knock-limited indicated mean effective pressure for two sparksettings. “
,
The variation of knock-limited indicated mean effectivepressure with blend composition of blends of S-4 plus 4 ml TELper gallon with M-4 plus 4 ml TEL per ga~lon am given in figure 3.Interpolated mixture-response curves of blends of the same refere-nce fuels for intervals of”S-percent concentration of S-4 areshown in figure 4. The ord+ate is a reciprocal scale and,because the data in figure 3 fall on straight lines, the curvesare equally spaced. A curve of clear S-4 is also shown on thisfigure.
.
Relation of knock lim$t to blend composition. - The varia-tion of knock-limited indicated mean effeotive pressure withblend composition of several fuels @ shown in figures 5 to 11.
6 “ NACA TN NO, 1374
The ordinatee are reciprocal scales of knock-limited indicated meaneffective pressure and the abscissas are linear scales of blendco?nyosltionexpressed as percentage by weight. Data are plottedfrcxnfigure 2 end table I, With the exception otieohexane at leanmixtures for a spark advance of 20° B.T,C, (fig. kl(a)), the datacan be represented by straight lties.
Triptane. - Triptane is oflepecial -interestl!ecauseit givesthe highest knock-limlted performance @ all the yaraffinic fuelstested. The knock-ltiited-mixture-reeponeecurves for pure trip-tane plus 4 rnlTEL per gallon at both @,rk eettings are efirapo-lated from data for blends with virgin base (fig. 2) aa shown infigure 12. The curves are equally spaced on a reciprocal ordinatescale because the data in figure 5 fall on straight lines. Theperfomwmce of triptane is greatly depreciated %y advancing the~park.
~rrelation of Icnockrat<ngs. - The assi ed ratings for the1?fuels studied at spark advances of 20° and 30 B.T.C. and also the
F-4 ratings =e present- in ta%le 31. Ratings above 100(expressed in terms of percentage S-4 with M-4) were estimated bymeans of’the straight-line extrapolation in figure 3. Similarext~apolations were used to obtain F-4 r@ings above 100.
The correlation of indicated mean effective pressure richagainst indicated mean effective pressure lean (knock-limitedtiep obtained from the full-scale air-cooled cylinder at fuel-air ratios of 0.10 and 0.067, reepectlvely),(fig. 13(a)) and ofindicated mean effective pressure at F-4 condition (knock-limlted Imep obtained from an F-4engine at a fuel-air ktio of0.11) against indicatedmesn effective pressure rich (fig. 14(a))al”egood for a epark aciv~ce of 200 B.T.C. The.data points forthe various paraffins scatter, however, on either side of thecorrelation line at a spark advanoe of 30° B.T.C. for indicatedmean effective pressqre rich against indicated me= effectivepressure lean (fig. 13(b)). This line is gstabllshed by the tworeference fuels, S-4 plus 4 ml TEL per gallon and the mixture of50-percent S-4 and 5.O-percentM-4 both.leaded to &ml TEL pergallon. This result Indicates that–as the severity of engineconditions wae increased, the constancy of engine ratings of oneparaffin in tame of two other paraffins did not-EZwaya hold.The indicated mean effective pressure at F-4 conditions againstindicated mean effective pressure rich also shows more deviationfrom the correlation line.as engine conditions were increased inseverity (fig. 14(b)). .
.
NACA TN No. 1374
Ratings expressed astainlng 4 ml TEL/gal) foraffective pressure of the
●
percentage 6-4 in M-4 .(h”othfuels con-equal knock-limited indicated meanparaffinic fuels at a spark advance
of 20° B.T.C. show good correlation when full-scale engine lean-mixture performance is plotted.against full-scale engine rich-mixture operation (fig. 15). The correlation is also good whenfull-scale engine rich-mitiure operation at 20° B.T.C. is “ylotted against the F-4 condition (fig. 16).
Ratings expressqd as ratios of knock-limited indicatedmean effective pessure of test fuel relative to indicatedmean etfective pressure of clear S-4 at either spark settingare not as constant for rich againet lean-mixture operation(fig.17) as they are forF-4 condition against rich-mixtureoperation (fig. 18).
SUMMARY OF REWLTS
From an investigation of aviation fuel components indi-vidually blended with virgin baee and alkylate to determine therelation between knock limit and blend composition and to com-pare methods of correlating the knock-limited data, the followingresults were obtained:
1. The knock-limited indicated mean effective pressure ofthe par”effinicfuels tested (with the exception of neohexane atlean mixtures for a spak advance of 20° B.T.C.) followed thereciprocal blending equation provided that the temperature ofthe cylinder walls near the knochtingzone was held constant.
2. mock-limited performance expressed in terms of percent-age S-4 in M-4 (both fuels contain 4 ml TEL/gal) to give anequal knock-limited indicated mean effective pressure gave ratingsof the pareffinic fuels tested that correlated better than ratingsexpressed by knock-limited indicated mean effective pressure orratio of indicated mean effective pressure of test fuel to theindicated mean effective pressure of cleer S-4 reference fuel.Correlation of ratings specified by ratio of indicated meaneffective pressure of test fuel to indicated mean effective pres-sure of clear S-4 reference fuel wae not as good,as the other twomethods.
8
3. Percentage of S-4 reference fueldn(both fuels containing 4 ml Z3ZL/gal)for an
NACA TN No. 1374
M-4 reference fuelequal knock-limited
i,ndi.catedmean effective pressure of the parti-finicfuels testedat a spark advance of 20° B.T.C. gave ratings of the p?affinicfuels that were independent or the type of engine used in theseruns.and-of the fuel-air ratio. However, the ratings were notindependent of the type of engine and the fuel-air ratio when thespark setting was increased from 20° to .30°B.’I.C..
Flight Propulsion Research Laboratory,National Advisory Committee for Aeronautics,
Cleveland, Ohio, June 4, 1947,
REFERENCES
1. Sanders, Newell D.: A Method of Estimating the nook Rating ofHydrocarbon Fuel Blends. NACA Rep. No. 760, 1943.
2. Sanders, Newell D., Hensley, Reece V., and Breitwieser, Ro1.and:Experimental Studies otthe ~ock-Limited Blending Character-istics of Aviation Fuels. I - Preliminary Tests in an Air-Cooled Cylinder. NACA ARR No. E4128, 1944.
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NACA TN No. 1374 9.
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TABLE I - I(HOOK-IJMITED IHDICATEDMEAK KFFZOTIVE PRESSURE OF ~~ OF AVIATION FUEL CONPOMENTSWITH BASE ~
ml-seal. air-cooled .yllnder~ compression ratio, 7.7; engine speed,2000 ~; inlet mixture temperature,2400 ~; qlinder~ead t
3erature
at exhaust end zone, SW F. All fuels oonteined 4 ml TEL/g
advanend
(percentby weight) Fuel-a% ratioD Fulbl
(perokt b~welght;:IRllmeD
cl-air ratio0.067 ● 10 0.067 ●1
[4& g:
I
s-4 M-4139 62.6 100 1S6
27.7 156 75.0 25:; 119 15572.3 I
baae10 1 15920:0 80:0 17730.2
I69.8
I199
39.8 60.2 221.--------- -------- -.------Hot-aoid VI inoctane br~ge10.0 1!3525.5 74:5 17139.9 60.1 18555,2 44.8 2077000 30.0 22480.3 19.7 246m54.8 45.2 22170.0 30.0 253
Neohexane lrginbase
13 5 16130:1 69:9 17445.1 54*9 lm864.7 35.383.8 16.2 225
40:0 60.0 --------Hot-aoLd
Y
octane89 9 210
24:9 75:145.0 55*O E:64.8 35.s ~49
185214
182200216241
--------
172189203231256
X
1671751s2
186214245279
176189
214233
+
241266272297
%291
)--------- ------- --------?!riptane pirgi.n I
%rt!!!rI%!50.0 50.0 1826001 39.9 206
hot-sold irgln
%Ti!!!H26500 I35.0 [ 172
I I)-------- - ------- --------,--------- ------- --------!--------- ------- --------P,80pentane lVlrgin I
bane122136
50.0 50.0 ● 146
3Se8 i 61.2 I 15055.2 44●S 16668.8 31.2 179
~eohexane virRln
53.0 47.0 16760.0 40.0 --------
r---------------- --------
174
-------
175201225256
-------
170186212237
-------
------.
166173
-------
174199222246
171188
208.--...
NAT 10NAL ADV t SORYCWI TTEE FOR AERONAUTICS
.10 NACA TN No. 1374.
.
TABLE II - COMPARISON OF KNOCK LIMITS OF 10 FUELS IN FULL-SOA~AIR-OOOIED CYLINDER AND F-4 ENGINE
For .aoh compound there ‘are three POWS of values: the first row 1s lmep,lb/8q im.j the seeond le percentage S-4 + 4 ml TEL/gal in M-4 + 4 ml~[fl~~ the third row is the ratio of imep of test fuel to lmep of
Compression ratio, 7.7; spark advamee~Q@ and 30° B.T.C.Jengine speeds 2000 r~l inlet mixture temperat=e~ 240° l?;cylinder-headtemperature at exhaust end zone, 3500 Fg.
IHot-acid cutane
I
4
I~eyreremo e I 4
Iaopent=e I 4(2+nethylbutane)
Allqlate 4
S-4 refereme ofuel
extrapolated from data for b
NATIONAL ADVISORYCWMITTEE FOR AERONAUTICS
9 a850 a700 a540 a760d; 125 124 123 1314.84 5.5s 3,68 6.94 4.63
, 1 1326 I ’360 I =s85 I *47
12mi:
I11105 I 108
● 2.’71
a310 281 345 a218108 105 109 104
2.03 1.84 1.82 2.40
233 244 268 198100 100 100 1001.62 1.60 1.41 2.20
=zg-1.59
a21096
1.37
23398
1*62
9!3.51.59
mm3
30112
2.11
a328112
2.14
2391001,56
‘2641051.72
a22097
1.44
‘%!-l‘$2l--?%1==1-=I139
77050.91
a9850
0.61
la!1.00
147 ~ 165 I 11476.5 I 76
I72
0.!3s 0.87 1.25
101 I 11050 50 I Yo
M!m_
153 I74
1.00 I
1114
0,7X
15374
1.00 I
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. NACA TN No. 1374 Fig. I
NATIONAL ADVISORYCOMMITTEE FOR AERONAUTICS
A Intake valve F Thermocoup 1e to measureB Rear spark plug temperature of combust ion-
C Exhaust valve chamber wal I at exhaustD Front spark plug end zone
E Exhaust end zone G Piston
Figure 1. - Approximate location of exhaust end zone.
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No. 1374 Fig. 2
khmxui. Ill
‘armob fU.Zws.nt slkrl~t. + 33,&Pcr-
$-... .dlpten.O-pmoontdilsopmpyl + a.p.r.● nt virgin h..Ot_&oid octm. m
E-
y I, 1 1 I 1 I I I
IE r I 1“1200 , 1 I
It 1#+=1—klI I
I
I I
I
1
7
._l L#JIx/Tlllwl[ll I
-.-I filxllllllll I 1/
lii~=iii~iii’v
lm
00
lao
160
aio
● ●06 ●M .10 .1? .04 .06 .0s .10,
.12?uel-As ratio
(a) Wk admloo, 200a.r.c. (b) Sparkadvanoe,30°B.T.G4
?igure2.- Xnoak-lla%tedperformanoa of aviation-fuelooupoaant8, basefuala, referencefuels,and blends of aviation-fwloompoaent● and basefuels.Jull-8celeair-coold cylinder:*K
&8 F: oyliadai-adQrwelon ratio, 7.71.nginespool,2$U)qm; inlet mixtum temperature,temperature ●t ●tiuetendcone,350 ?.
Fig. 3 NACA TN NO. 1374 .
loo&
r’ ~NATIONAL AOVISORY
COtWITTEE FOR AERONAUTICS t00
It
00
t/ /
t
&/? 1 /
350
300 ))1 c,28o
dlt 1
260A i J .’!/
*O
20019018o , Yf I /
170 A ‘1
160 / Y 1 { 7
150 , 1 /Fuel-air
m .rat 10 / ‘ .0.10
%30.067, [
120
110 /c1
1 b60 ao Xm lgo 60 m 100 120
S-kM blind,Pcreeatbywoi~t
(a) Spark advance, 20° B.T.O. (b) 6park ●dvanoo, 30° B.T.O.
3.WI
‘%*uels oont.Ln 4ml TSfer gallon. K:;:;ZtG’22;ti2;~?$~~t~-4”e 3. - hlation of knook limit to oom
0013 reaeion ratio, 7.7; eng ne mee~, m m; inlet Mixture temeratureIg240 F; oylinder.headtemperatureat e%huuatend sone, 350°T.
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NACA TN NO: 1374 Fig. 4
2 PO?%olltago S-4 ● 481 T2L# al ,vlth M-4 ● 4 ml Twg 0!
260 — —
180
170
160
4~ 60 \ ,/ 70 —
#0*- tfi ●* -#e* / /4 ,* -.--”
$’● d 4 # ..-
***. --
Q
L30I
‘t
;b
100
95 Fuel❑ 50-peraent S-4 +
9 0 rperaent M-4 + 4 m TWgalO S-4 + 4ml T&/gal t,Q S-4 Q
8 5
8 0
75NATIONAL ADVISC8Y
COMMITTEE FOR AERONAUTICS
.04 .06 .0s ,10 .12
Fue14ir ratio
(a) Spark advance, 20° B.T.O. (b) -k advanae, >0 B.T.O.
~i re 4. . Blen-n obaraoto~le%loeof S-4 andM-4 refarenee fuelsPlue @mlE& per gallon. h-male ●ir-ofaoled oyllnder; em
; eyllndek-ki”engine ●peed, S000 rpm; lmletmixture temperature,~e:ion ratio
A
temperature at exhaust ●nd zone, 350° F.
Fig. 5 NACA TN No. 1374
0 25 9 75 1000 25 w 75 100
Triptme in blond, pement by weight
(a) Spark advaneo, 20° B.TOO. (b) Spark ●dvanoe, ~“ B.T.C.
. - Relationof knook limit to oom~eition of blend- of tri tan. with virgin“~:~ntainin&4 mlT=per@llon. fill-a~le .ir-oooledoylin~~r;wmpreamion
ratiov 7.7; engine speed,2000 rpm; inletmtiture temperature, 240 F; oyllnder-hsad temperature●t exltaust end aone, 3~e S,
.
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●
NACA TN No. 1374 Fig. 6
.
Iwo
!?~ NATIONAL AOVISORYCOMMITTEE FOR AERONAUTICS
00
&J ~
350
28o260240 #
200190lao
160
150
*O
130
120
0 m 40 60 so 100
tiiptanein blend,pereeut by V4CM
Figure 6. - Relationof hook llmlt to oompositlonof blends of t~iptanewith alkylateoontalnlng 4 ml TEL per gallon. Full-6oalealr-oooledcylinder; compre8810nratio,7.7; engine 8pee6,2000 rpm-t &nLet =*twe temperature 240° F; oyllnder-headtempa~a.ture 8t exhauatend zone, 350 F; spark advanoe, 20° B:T.C.
.
Fig. 7
.
NACA TN No. 1374 ●
✎
.—
1;@o350
300280
260
u
220
II NATIONAL ADVISORY t I I 1 I
COW ITTEE FOR AER@wJTICS
*
1 Tu:;i:irI
I8
0.10 0Ill .067 Y
. T1/ o
/ 0/m. A190Mom
A%
n n 1 K I 1 1 I I F 1 I 1 I I !
0 25 P 75 100?lot-aoidootanein blond,poroent by wgight
(a) Spark advanoe, 20° B.T.C. (b) 8parkadvano8, @ S.7.6.Figure 7. - Relationof knook llmlt to oonpoaltlon of blondsof hot-aoidootmo w$th
vlrgln base oontainlng 4 al TEL par anon.
!
fill-soalealr-ooolodo Mnder; oompra$sionratio, 7.7; engine speed, 2000 rpm; nlet mixturetemperature,240° $; oylinder-lwadtemperature at e~ust ●nd zone, 350 F,
●
.
.
.
NACA TN No. 1374 Fig. 8
lmNAT 10NAL AOV I SORY
rCORWITTEE FOR AERW4AUTICS
00
400
30028o
240220
200190
150
130
120
1000 20 40 60 m 100
Zot-acidootane in blend, peroentby weight
Figureg. . Relationof knoolcllmlt to oompoeltlonof blends of hot-soldootanewithalkylateoontalnlng4 ml TEL per gallon. fill-eoalealr-oooledoyllnder;oompresslonratio, 7.7; engine speed, 2000 ZWZ; &nlet mixture tamperat~e, 2k@ F; oyllnder-headtaIzperatureat exhauatend zone, 350 T; spark ad~ce, 20 B.T.O.
.
Fig. 9 NACA TN NO. 1374
m NATIONAL ADV ISCRY 1 I I
z%COWAITTEE FOR AERONAUTICS
400
350
m
260
a220 ./
w190
170
d150
&orat Lo
*o 0.1 /
130 ❑ Ii!.0 7{
3120
[1
110
100Lo 25 %J 75 1000 25 w 75 lm
Ieopentanelo blend, peroentb~ weight
(a) Epark ●d*anoe, 20° B.T.O. (b) Spark advance,~“ B.T.U.?lgure9. - Relationof knook lldt to oonpositlonof blendeof isopentanewith
vlrgln base oontalnlng 4 al T= per gallon. Full-eoalealr-oooledoyllnder;oompreealon ratio, 7.7; engine speed, 2000 W; inletmixture tenperatura,24& F; oyllnder-head temperatureat exhauaten~ zona,350° T.
.
.
.
NACA TN NO. 1374 Fig. 10
.
lm800
E% ~
NATIONAL ADVISORYCOFWITTEE FOR AERONAUTICS
& .
,
@
350 . -/./ /
/ ‘d /’0
:! . -A /
260 + &
240
{
lao
170
160. /150 / c{ 1
Tu:ui:ir
@’ / ‘
810.1
130..0 7 IY
320f
110,
lm.o 25 50 75 100
0 25 50 75 lm
Dlieopropylin blend, peroent by weight
(a) Sperkadvanoe, 20° B.T.G. (b) Sparkadvanee, y“ B.T.O.?igure10. . Relationof knook limit to compositionof blendsof diisopropylwith virginbase containing 4 ml T2L per gallon. ~-soale ●ir-oooledo~Under; ooapreseionratio, 7.7; engine speed, 2000 rpz; Inletmixturetemperature,240° F; oylinder-headtemperature at exhaustend zone, 350° ~.
Fig. II NACA TN No. 1374
.
----
800 NATIONAL ADVISORY I
ECCWMITTEE FOR AERONAUTICS
G
m
35Q
260
abo
220
200 —190MO —
160
150
*Oo 0010
130•1 .067
120~ /
c
110
lao * 9 75 100
0 s 9 75 100Meaheaaueh blena, percent br weight
(a) Spark advaaae, & B.T.U. (b) Spark advanae, + B.T.G.
?@me 11.-Relatlonor ~ak Mmlt to aompositlonof blends of naohexaneuith*labaee matalnl
•s~~onratio, 73; e%ae meed, 2000 q=; inht mixture teaper.tw., 240° F;TEL Per gallon. $’ull-soaleair-moled cylinder;
%H%er-head temperatureat exhaust end zone, ~% F.
.
.
.
NACA TN No. 1374 Fig. 12.
b
.
Uoc70C60C
5=
40C39
3002SC26C
24U
22a
200190180
170160
150
140
lyl
120
110
100
95
90
85
m
75
70
NATIONAL ADVISORYCOMMITTEE FOR AERWAUTICS
;9
\ If --- - I I b I ---w -- ..-. -
-- 1 #.-f .
11 .-*-x. ---
I
/ 6+
1 r4
) /
e 1
J xx ~*
t /
d<
//
0 Vtigln base + 4ml T2L/@
percent vlrg,n bme + ?“;l ,+ 50-peroent triptane +
T=/@o 1
‘—---- Trlptane 4 ml TELfgal(extrapolated curve) 1
.04 .06 .0s .10 .12
.04 .06 .Og .10 .12
Puel-aLrratio
(a) Sparkadwinoe,2Q” B.T.C. (b) ~2dYluM3S, no B.T.C.
Rlgure12. - Extrapolatedknodltilted nixture-re~nse ourre for triptaneplus4 ml 51Z pergallon. ?ull-eoalesi>oooled @inder; compressionratio,7.7;engineqeed, 2000 w Inletmixturetemperature, 240° Pg qrlinder-hea~temperatureat exhaustend sone,350°Z’.
Fig. i3a NACA TN No. 1374 .
1
, ,r I I I I 1 1 I.
80 90 100 150 200 300 500 1000 ~
Yuel
TriptaneDllsopropylHO:-acid octane
NeohexaneXsopentaneAlkylateVirgin base50-percentS-4+50-peroentM-4
All fuels oontaln 4.0 ml TEL/gal
Kno&-limited lamp at fuel-k ratio of 0.10, lb/sq in.(reeiproealsoale)
(a) Xndloated mean effeetive pressures at spark advanoe of 20° B.T.C.
?1 E 13. - Oorrelatlon between knock Mrnlta at rich and lean mixtures.l-scale alr-oooledcylinder; compressionratio, 7.7; engine speed,
2000 m; inlet mixture temperature, 240° F: cylinder-head temperatureat exhaust end sone, ~ F.
.
.
.
NACA TN No. 1374
500‘
300
200
150‘
100
Fig.
a DllaopropylA Hot-add ootane
xl Neohexane
❑ 50-percentS-4+50-peroentM-4
All tuela oontaln 4.0 ml TEL/gal
80 90 100 150 200 300 500 1000 =
Knook-limitedlmep at fuel-airratio o 0.10, lb/sq in..(reolprocalscalei
(b) Indloatedmean effeotive pressures at spark advanoe of 30° B.T.6.
FZgure13. - Goncluded. Correlationbetweenknock llmitsat rioh and leanmixtures. ~11-soale alr-cooledcylinder;compressionratio, 7.7; en@Mspeed, 2000 rpm; inlet mixturetemperature,240° F; Oyllnder-headtempera-ture at exhaustend zone, 330° ~.
Fig. 14a NACA TN No. 1374.
.
d’o*
10
5
3
2
1
1
80 90 100 150 200 300 500 1000 =
Kno~k-l~ltod ~ep in full-eoaleair-oooletloyllnderatfuel-airratio of 0.10, lb/eq in. (reolprooalSOalO)
(a) Indicatedmean ●ffeotivepressuresat spark advanoeof 20° B.T,C.
?l@re 14. . Correlationbetweenknook.ltilteddata obtainedat F-4 oondl-t%on~ and in full-male air-oooledcylinderat-the followingoondltione:Oompreseionratio, 7.7; engine speed, 2000 rpm; inletmixture t-Perature,@@ FZ oyllnder-headtemperatureat exhauet end sone, ~~” F.
.
.
●
.
.
.
.
NACA TN NO. 1374.
Fig. 14b
d“d
!!
10C
9C
8C
?C“
1
Fuel
& TrtptaneO DilsoProPylA !iot-aoidoctaneo S-4w Neohexaneo IsopentaneO Virgin baseO ~-percent ~%0-peroent H-4
All ruels oontaln 4.0 ml Twgal
80 90 100 150 200 300 500 1000 ~
Kaoek-llmltedimp in full-scaleair-cooledcyllnderatfuel-a3rratioof’O.10,lb/sqtn. (reclprooalsoale)
(b) Xndlcatedmean effective pressures at sparkadvanceof ~ B.T.G.
Figure 14.- Coaeluded.Correlationbetweeuknock-llmiteddata obtainedat F-4 conditionsand In full-scaleair-cooled oyllnderat the follow-lng conditions;Compress on ratio, 7.7; en@ne speed,2000rpm; inlet
d~~~$~~t~e, 2
F; cylinder-headtemperatureat exhaust end
Fig. 15 ~ACA TN NO. 1374
NATIONAL ADVISORYCCUMITTEE FOR AERONAUTICS
.
b
160 ;
140
120 .
1001.
80 :
4
60 “
~,:/
M#”40
Spark advanoe(deg B.T.O.]
hel
20 30
b TMptanek DilsoproPyl
: A Hot-aeLd octanev \ Neohexane ~aliu m Isopentane
Alkylate; Q Vlrgln base
All fuels oontain /
b ml ~gal //
..
#
/
.
●
.
.
./
/
/..
/●
60 80 120 14Q 160
Xntmk ratingat fuel-airratto of 0.10Figure 15. - Correlationof knook-llrsitedrat
9s ●t rioh and lean
mixturesexpressed as peroen%0
e of S-4 plus ti 21Z per gallonw~th M-4 plus 4 ml TR per ga n. ?ull-soale air.0001ed oylinder;oompress$on ratio, 7.7; enginespeed,2000 rpm; inletmixturetemperature,24@ ~; Oyllnde-head tempezmtureat ●xhaust ●nd zone,35@ r.
.
NACATN NO. 1374 Fig. 16.
.
.
.
.
.
140
120
100
80
60
40
NATIONAL ADVISORYCOMMITTEE FOR AERONAUTICS
.
.
,
Neohexane ..
Alkylate;
..● Q Virginbase
All fuels oontain Matohb ml TEL/gal line
~●
/...
t3
/●
P ~1
T .4
..
PdJ
/ *..
./●
a
/.
//
t /./ .
●
40 60 go 100 120 140
Knook ratings in full-scale alr-oooleclcylindera% fuel-air ratio or 0.10
F@ure 16. - Correlation of knock-limlted ratings expressed aspercentage S-4 plus 4ml TEL per gallon wlthM-$ plus 4ml TELper gallon. Data obtained at F-4 oondltions and in full-soaleair-cooled oylinder at followl
Yoonditiohs: Compression r tie,
7.7; engine Speed, 2000 mm; in et mixture temperature, 2408 F;oyllnder-head temperature a% exhaust end zone, 350° F.
Fig. 17 NACA TN NO. 1374
Spark advanoe(deg B.T.C.)20 30
o Q❑ n
1 i
Fuel INATIWAL ADVISORY
CWITTEE FOR AERONAUTICS 3
TriptaneDiisopropylH&aoid octane
NeohexaneIsopentaneAlkylateVirgin base50-percsnt S-k+50-peroent M-4
All fuels aontain4 ml TEL/gal
1 1 I I
I /1 w 1I1 I
I I
i
I I
III [ /1 I
1/1 .-.
.5 ,
1// .
c /
I/ Matcn
lineb ; I
I/
//
/ ●
3 . A..
2
oo~ ’’”’””’’’’’’’’”’’’’’”” ‘“’’l ’’’’l’.” ●S’” ’” ’’’’ ”’’”’ ”*”l1 2 3 5
Xnouk-limited lmep ratio at fuel-alrratio of 0.10
Ptgure 17. - Correlationof knook-llmitedratings expressedasratios of knock-limitedindicatedmean effectivepressureoftest fuel relativeto clear S-4 reference fuel. Full-soaleair-oooledcyllnder; compression ratio
dj;
2000 rpm; inlet m*ture temperature, 2 ;temperature at exhaust end zone, 350° F.
engine speed,oylinder-head
.
.
.
.
. NACA TN
.
NO. 1374 Fig.
\.
.
.
.
7au
ii
COMMITTEE FOR AERONAUTICS
dA 2
.
6 ;+50-peroent H-4 ●
,
.
.
.
.
.
.2 ...
.
.
00 1 2 3 4 5 6Knock-llmited imep ratio for full-scale alr-oooled cylinder
at fuel-alr ratio Or 0.10
@ure M. - Correlation of knook-llmlted ratings expressed asratios of knock-llalted lndloated mean effeotlve
Bressure Or
test fuelrelativeto dear S-4 refereneefuel. ata obtainedat F-4 conditions and in tull-scalealr-oooled eyllnder atfOllOWillgoon~itlons: impression.ratio . ; enginespeed,$72000 rpm; inletmixture temperature, 240A ; cylinder-headtemperature at exhaustend zone, 3500 F.
18
KDIPFOWGS (BfOtt)
T7ear, Jerrold D. Sanders, N. D.
AUTHOR(S)
DIVISION: Fuels and Lubricants (12) SECTION: Analysis and Testing (8) CROSS REFERENCES: Fuels, Antiknock - Testing (142622)
AftD- 9207 CQIG. AGENCY NUM3H1
1H-137U
REVISION
AMER. TITLE: Experimental studies of the knock-limited blending characteristics of aviation fuels - II - Investigation of leaded paraffinlc fuels 1n an air-cooled cylinder
FORG'N. TITLE:
ORIGINATING AGENCY: National Advisory Committee for Aeronautics, Washington, D. C. TRANSLATION:
COUNTRY U.S.
LANGUAGE FORG'NCLASS U. S.CLASS. DATE Eng. Unclass. Jul'l)7
PAGES 29
ILLUS. 22
FEATURES photos, tables, graphs
An investigation was made to determine the relation between knock limit and blend composition of selected aviation fuel components Individually blended with virgin base and alkylate. These tests were carried out in an air-cooled aircraft engine cylinder. Results Indicated that the knock limited Indicated mean effective pressures of the paraf- flnlc fuels investigated, except the neonhexane blends at lean mixtures for a spark advance of 20° BTC followed the reciprocal blending equation provided the temperature of the cylinder walls near the knocking zone was held constant.
NOTE: Requests for copies must be addressed to N.A.C.A., nashlngton, D. C.
T-2. HQ.. AIR MATERIEL COMMAND AlR VECHNICAL ONDEX WRIGHT FIELD. OHIO. USAAF /-' t7M>-31 HAD 47 ZZX
