WaveCatcher intakes for

scramjets

Sannu Mölder

McGill University, Montreal, Canada

Ryerson University, Toronto, Canada

1

Acknowledgements

George Emanuel

François Lesage

Seyed Miri

Hideaki Ogawa

Julian Romeskie

Rabi Tahir

Evgeny Timofeev

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History

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With growing emphasis on obtaininghigher and higher Mach numbers insupersonic flight of turbojet and ramjetpowered aircraft, the necessity ofmaximizing the inlet diffuser pressurerecovery of the propulsion system hasbecome increasingly evident during thelast few years.

Dr. Rudolf Hermann (1956)

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McGill/BRL HARPMcGill/NRC Martlet-Scram

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Martlet/Scram (Molder/Romeskie -1972)

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REST (Smart)

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REST Scramjet Engine Model

•Mach 4.8-6.0 testing commenced in March 2005 in the Combustion Heated Scramjet Test Facility (CHSTF) at Langley

•Mach 4.8-7.5 testing in the Arc Heated Scramjet Test Facility (AHSTF) in planning 9

APL/JHU

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Billig, Kiersey, Snow, VanWie (1960)

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Intake design

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Intake design concerns

Capability

StartingEfficiency

Me/Mi

tp yes/no

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Intake design targets

Capability

StartingEfficiency

Tign

MAXyes

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“Nominal” hypersonic air intake

• Mach number change 8 to 4.5 or 3

• Flight altitude 30 km

• Reynolds number 1.79*106

• Exit diameter 20 cm

• Contraction ratio 11.1 to 1

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Basal (inviscid) flows for

WaveCatching

• Planar flow - Wedge, P-M compression.

• Axial flow – inside conical surface

• Axial/conical - Taylor-Mccoll, cone,

Busemann

• Lens analogy (LA) (planar and axial)

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Flow in straight conical duct

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Four types of axial conical flow

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T-M equations

The Taylor-Mccoll equation may be

expressed in (r, )-components of the

Mach number, u and v.

1

cot

2

12

v

vuuvv

d

du

2

2

1 cot1

2 1

dv u vu v

d v

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Busemann flow

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CFD of Busemann flow at leading edge

Timofeev

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Schlieren picture of exit flow

M=3

Focal point Waves from

trailing edge

Freestanding shockConical

Centered

Compression

fan

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Pressure at the hot-spot

Lesage

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Busemann intake

• Mach 8 to Mach 4.5

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Viscous Busemann flow

inviscid

viscous

Ogawa

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Total pressure recovery on full

Busemann intake

Inviscid flow 97%

M=8 alt=30km

D=20 cm Re = 1.79*106

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Total pressure recovery on full

Busemann intake

Inviscid flow 97%

Viscous flow 42%

M=8 alt=30km

D=20 cm Re = 1.79*106

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Truncation and

Stunting

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Reason for truncation

decrease b.l. losses

(centered axial compression fan)

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Truncation and stunting

truncation

stunting

full length

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Contraction ratio

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Pressure ratio

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Exit Mach number

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Total pressure recovery

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Effects of Truncation & Stunting

* 2 to 3% increase in efficiency at 20%.

* Weight saving (~30%) obtainable at 20%

truncation or stunting

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Busemann/cone intake

Conical flow throughout; Annular exit

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Lens analogy LA (Emanuel)

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Lens analogy

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Lens analogy analysis

* Flow is shockless – isentropic.

* For planar LA flow the surface

coordinates are given by explicit, algebraic

expressions.

* For axial LA flow, the MOC has to be

used to find the surface coordinates.

* At M < 1.37 limit lines appear.

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Lens analogy isobars by CFD

M 3 to 2 for planar flow

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Ogawa

WaveCatchers

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WaveRiding

* to design airplanes

* external flow

* maximize L/D

WaveCatching

* to design intakes

* internal flow

* maximize

performance

Streamline tracing

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WaveCatcher

• Offers an analytical and rational design environment with a wide choice of intake geometry.

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WaveCatcher

• Offers an analytical and rational design environment with a wide choice of intake geometry.

• Offers uniform and parallel flows.

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WaveCatcher

• Offers an analytical and rational design environment with a wide choice of intake geometry.

• Offers uniform and parallel flows.

• Offers overboard spillage to facilitate intake flow starting.

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WaveCatcher

• Offers an analytical and rational design environment with a wide choice of intake geometry.

• Offers uniform and parallel flows.

• Offers overboard spillage to facilitate intake flow starting.

• Offers swept leading edges to alleviate heat transfer.

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WaveCatcher

• Offers an analytical and rational design environment with a wide choice of intake geometry.

• Offers uniform and parallel flows.

• Offers overboard spillage to facilitate intake flow starting.

• Offers swept leading edges to alleviate heat transfer.

• Offers small modules that can be individually tested.

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Superelliptic streamtube

1

21

21

nm

b

y

a

z

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4-module wavecatcher Busemann

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Flowpath morphing

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WaveCatcher

startability

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Design for intake flow starting

• Intake starting is a MUST

• Capability or efficiency have to be

compromised to obtain started intake flow

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Kantrowitz area and Mach number

Kantrowitz starting criterion based on analysis assuming:

steady flow

isentropic flow

normal shock

Kantrowitz criterion is a guide and a starting point.

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Me >

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unstarted

starting

started

Kantrowitz Mach number MK and

area AK

0,, eK MMf

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Kantrowitz Mach number MK and

area AK

066.*1.1 eK MM

0,, eK MMf

For = 1.4,

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Kantrowitz Mach number MK and

area AK

1.101* .066K eM M

0,, eK MMf

For = 1.4,

1

2 12

2

11

21

12

KK i

i Ki

MA M

A MM

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Bow shock to K-position!

• Overspeeding – effective for area ratios

0.6 to 1. Of no interest to scramjets.

• Intake acceleration – 10 000 g’s

• Area change – possible

• Perforations – possible, large mass spill

• Overboard spillage

• Unsteady flow - diaphragm rupture DRIPS

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Strong shock start design

with spillage

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Busemann strong

shock design

O

v

e

r

b

o

a

r

d

s

p

i

l

l

a

g

e

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Diaphragm

Rupture

Initiated

Pulse

Starting

DRIPS

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stopping shock

starting shock

DRIPS (8 ms after DR)

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Busemann shape M 8

to 4.5

Area ratio 11.2

Pressure ratio 33

DR at t = 0

Inviscid flow

Plenum p = .01

Diaphragm mass 0

Start!

DRIPS

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Busemann shape M 8

to 4.5

Area ratio 11.2

Pressure ratio 33

DR at t = 0

Viscous flow

Plenum p = .01

Diaphragm mass 0

No start!

DRIPS

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Busemann shape M 8

to 4.5

Area ratio 11.2

Pressure ratio 33

DR at t = 0

Inviscid flow

Plenum p = .02

Diaphragm mass 0

No start!

DRIPS

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Busemann shape M 8

to 4.5

Area ratio 11.2

Pressure ratio 33

DR at t = 0

Inviscid flow

Plenum p = .01

Diaphragm mass

1kg/m^2

No start!

DRIPS

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DRIPS non-start

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DRIPS - Mach 6; A3/A1=.31

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DRIPS – Mach 6; A3/A1=0.1

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Started 4-module intake

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Exit

smolder@sympatico.ca

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Taylor-Mccoll equation governing

conical flow

2 22

2

2

2

11 2 cot

2

0

dU dU d UU U

d d d

dU dU dU d UU

d d d d

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