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WaveCatcher intakes for scramjets Sannu Mölder McGill University, Montreal, Canada Ryerson University, Toronto, Canada 1
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
2
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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5
McGill/BRL HARPMcGill/NRC Martlet-Scram
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Martlet/Scram (Molder/Romeskie -1972)
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REST (Smart)
8
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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12
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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
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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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25
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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57
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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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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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