parametric study of the performance of two-dimensional...

Parametric study of the performance of two-dimensional scramjet intake

V. Jagadish BabuPratik Raje, Rachit Singh, Subhajit Roy, Krishnendu Sinha

Department of Aerospace Engineering, IIT Bombay

18th Annual CFD Symposium, August 10-11, 2016, Bangalore

Vemula (IIT-B) Scramjet design 1 / 31

Schematic of scramjet engine

Outline

1 Schematic of scramjet engine

2 Objective

3 Inlet design

4 On-design condition

5 Mach effect

6 Effect of angle of attack

7 Effect of cowl deflection angle

8 Starting of intake

9 Summary




Inlet Combustor Nozzle




Primary objectives in designing efficient inlet

isolator

Ramp1Ramp2

Ramp3

Airintake system

1 Near to isentropic and high pressure recovery.2 High capture area (high mass flow).3 Uniform flow.4 Wide range of operation.



Performance parameters

Static temperature ratio

ψ = TexitTinlet

Static pressure ratio

r = PexitPinlet

Total pressure ratio

πc =Po,exit

Po,inlet

Kinetic energy efficiency

ηKE = 1 − 0.2(

1 − MexitMinlet

)5

Captured mass flow ratemc = ρAcVinlet

Ac

A0

Aexit

Inlet Outlet


Objective

Outline


2 Objective

3 Inlet design


5 Mach effect




9 Summary


Objective

Objective

1 Design a scramjet inlet (at a cruising flight Mach number-6.5).2 Effect of angle of attack, α.3 Effect of cowl deflection angle, θc.


Inlet design

Outline


2 Objective

3 Inlet design


5 Mach effect




9 Summary


Inlet design

Inlet Design

Design criteria:1 Shock-on-lip condition2 Uniform flow

A B

C

D

C’M

E

F

β2

β1

β3

A’

Input parameters1 Mach number (M)2 First ramp length (AA’).3 Distance of the cowl tip from the first ramp leading edge (AB).4 Total intake height (DB).


Inlet design

Physical and Computational domain

Details of scramjet intake geometry (All dimensions are in meters)

0.40.5

0.9

0.0367

0.3

11.52o

15.28o

0.5906


Inlet design

Physical and Computational domain

Grid structure and boundary conditions.

x

y

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6

0

0.2

0.4

0.6

Supersonic exit

Inviscid WallFree Stream

Inviscid Wall

Supersonic exit

Cowltip

Ramp2 Isolator

Ramp1

550 x 250 grid points, with x-stretching factor of 1.28


Inlet design

Numerical methodology

1 In-house code2 Finite volume formulation3 Modified Steger-Warming flux splitting (Computers and Fluids, 1989)

4 Implicit Data Parallel Line Relaxation method (AIAA, 1998)

J. Propul. Power (2012) AeSI CFD Sym. (2009)


On-design condition

Outline


2 Objective

3 Inlet design


5 Mach effect




9 Summary


On-design condition

On-design condition (M = 6.5)

x

y

0 0.5 10

0.1

0.2

0.3P/P∞: 2 5 8 11 14 17 20 23 26 35

Ramp1 shock

Ramp2 shock

cowl tip

Expansion corner

M = 6.5, T = 219.3K, ρ = 0.0343 kg/m3

Cowl shock

Pressure contour of inlet for on-design Mach number at α = 0◦ and θc = 0◦.


Mach effect

Outline


2 Objective

3 Inlet design


5 Mach effect




9 Summary


Mach effect

Mach effect

Table : Comparison of the analytical and numerical simulation results with respect to various parameters forscramjet inlet.

Mach Tiso/Tinlet Po,iso/Po,inlet Piso/Pinlet MisoTheo. CFD Theo. CFD Theo. CFD Theo. CFD

4.5 2.298 2.295 0.742 0.745 13.660 13.652 2.446 2.4505.5 2.716 2.707 0.630 0.637 20.804 20.797 2.824 2.8306.5 3.197 3.197 0.521 0.523 30.422 30.533 3.127 3.1207.5 3.743 3.76 0.422 0.414 42.827 42.769 3.370 3.370

The difference is within the ±2 % error range for all parameters.


Effect of angle of attack

Outline


2 Objective

3 Inlet design


5 Mach effect




9 Summary



Flow structure for varying α at M = 6.5

x

y

0 0.5 10

0.1

0.2

0.3P/P∞: 2 4 6 8 10 12 14 16 18 20 22 24 26 28

Ramp1 shock

Ramp2 shock

cowl tip

Expansion corner

M = 6.5, T = 219.3K, ρ = 0.0343 kg/m3, α = 3

0

Cowl shock

Expansion fan

(a) α = −3◦

x

y

0 0.5 10

0.1

0.2

0.3P/P∞: 5 20 35 50 65 80 95 110 125 140 155 170

Ramp1 shock

Ramp2 shock

cowl tip

Expansion corner

M = 6.5, T = 219.3K, ρ = 0.0343 kg/m3, α = 6

0

Cowl shock

Expansion fan

Reflected shock

(b) α = 6◦

Pressure contour for varying α at Mach 6.5 and θc = 0◦.Vemula (IIT-B) Scramjet design 17 / 31


Performance parameters (varying α and M)

M

Texit

/T

inle

t

4 4.5 5 5.5 6 6.5 7 7.5 82

2.5

3

3.5

4

4.5

5

5.5

6

α = 3

α = 0

α = 3

α = 6

M

Pexit

/P

inle

t

4 4.5 5 5.5 6 6.5 7 7.5 810

20

30

40

50

60

70α = 3

α = 0

α = 3

α = 6

∴

At the fixed angle of attack, the strength of the shocks increases with increasing Mach number



Continue...

M

ηK

E_

E

4 4.5 5 5.5 6 6.5 7 7.5 80.96

0.965

0.97

0.975

0.98

0.985

0.99

0.995

1

α = 3

α = 0

α = 3

α = 6

M

P0

,exit

/P

0,in

let

4 4.5 5 5.5 6 6.5 7 7.5 80.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

α = 3

α = 0

α = 3

α = 6

Maximum ηKE is observed at designed Mach number


Effect of cowl deflection angle

Outline


2 Objective

3 Inlet design


5 Mach effect




9 Summary



Flow structure for varying θc at M = 6.5

x

y

0 0.5 1 1.50

0.1

0.2

0.3P/P∞: 2 5 8 11 14 17 20 23 26 29 32

M = 6.5, T = 219.3K, ρ = 0.0343 kg/m3, θ

c= 3

0

Ramp1 shock

Ramp2 shock

Cowl tip

Expansion corner

Cowl shock

Hinge shock

Expansion fan

(a) θc = 3◦

x

y

0 0.5 1 1.50

0.1

0.2

0.3P/P∞: 2 6 10 14 18 22 26 30 34

M = 6.5, T = 219.3K, ρ=0.0343kg/m3, θ

c= 9

0

Ramp1 shock

Ramp2 shock

Cowl tip

Expansion corner

Cowl shock Hinge shock

Expansion fan

(b) θc = 9◦

Pressure contour for varying θc at Mach 6.5 and α = 0◦.Vemula (IIT-B) Scramjet design 21 / 31


Performance parameters (varying Mach number and θc)

M

Texit

/T

inle

t

4 4.5 5 5.5 6 6.5 7 7.5 8

2

2.2

2.4

2.6

2.8

3

3.2

3.4

3.6

3.8

θc= 0

θc= 3

θc= 6

θc= 9

M

Pexit

/P

inle

t

4 4.5 5 5.5 6 6.5 7 7.5 85

10

15

20

25

30

35

40

θc= 0

θc= 3

θc= 6

θc= 9

Compression ratios increases with MDecreases with increasing θc



Continue...

M

ηK

E_

eff

4 4.5 5 5.5 6 6.5 7 7.5 8

0.986

0.988

0.99

0.992

0.994

0.996

0.998

1

θc= 0

θc= 3

θc= 6

θc= 9

M

P0

,exit

/P

0,in

let

4 4.5 5 5.5 6 6.5 7 7.5 8

0.3

0.4

0.5

0.6

0.7

θc= 0

θc= 3

θc= 6

θc= 9

↑ θc– shifts the maximum ηKE to lower Mach numbers


Starting of intake

Outline


2 Objective

3 Inlet design


5 Mach effect




9 Summary


Starting of intake

Flow initialization

x

u = V∞

v = 0

Earlier simulations: Free-stream velocity initialization

x

u = V∞

v = 0

u = 0

v = 0

New Simulations: Zero velocity initialization


Starting of intake

Unstarted mode

P/P∞: 1.5 5.5 9.5 13.5 17.5 21.5 25.5

3000 iterations

P/P∞: 1.5 5.5 9.5 13.5 17.5 21.5 25.5

5000 iterations

P/P∞: 2 8 14 20 26 32 38 44 50 56 62 68

7000 iterations

P/P∞: 2 8 14 20 26 32 38 44 50 56 62 68

8000 iterations

P/P∞: 2 22 42 62 82 102 122 142

10000 iterations

P/P∞: 2 36 70 104 138 172 206 240

12000 iterations

P/P∞: 2 30 124 152 180 208 236 264

13000 iterations

P/P∞: 2 18 34 130 152 168 184 200

14000 iterations


Starting of intake

Starting criteria

(Ae/As) >

[γ − 1γ + 1

+2

(γ + 1)M23

] 12[

2γγ + 1

− γ − 1(γ + 1)M2

3

] 1γ−1

Ae is fixed and reducing the As by deflecting the cowl to meet Kantrowitz criteriaSelf starting is achieved , θc = 9◦


Starting of intake

Started modeP/P∞: 1.5 5.5 9.5 13.5 17.5 21.5 25.5

3000 iterations

P/P∞: 1.5 5.5 9.5 13.5 17.5 21.5 25.5

5000 iterations

P/P∞: 1.5 5.5 9.5 13.5 17.5 21.5 25.5

7000 iterations

P/P∞: 1.5 5.5 9.5 13.5 17.5 21.5 25.5

8000 iterations

P/P∞: 1.5 5.5 9.5 13.5 17.5 21.5 25.5

10000 iterations

P/P∞: 1.5 5.5 9.5 13.5 17.5 21.5 25.5

12000 iterations

P/P∞: 1.5 5.5 9.5 13.5 17.5 21.5 25.5

13000 iterations

P/P∞: 1.5 5.5 9.5 13.5 17.5 21.5 25.5

14000 iterations


Summary

Outline


2 Objective

3 Inlet design


5 Mach effect




9 Summary


Summary

Summary

1 Performed inviscid numerical simulations of a typical mixed-compression scramjet intake.2 Studied its performance for a range of Mach numbers, angles of attack and cowl deflection

angles.3 At off-design conditions, a set of shock and expansion fans are generated in the intake

duct, and they reflect between the duct walls.4 It is found that the maximum pressure recovery is obtained at lower Mach number with

weaker shock waves, and the capture mass flow rate is maximum at higher Mach numbers.5 As the cowl angle is increased, the maximum kinetic energy efficiency is obtained at Mach

numbers lower than the design point.6 At zero velocity initialization, intake starts with deflection of cowl.


Summary

Thank you...


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