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Nozzle of turbojet engine

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Old   January 6, 2014, 17:18
Default Nozzle of turbojet engine
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KK
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Hello,

I want to count the heat exchange in the nozzle of turbojet engine. I've created a model of this engine and I used following settings:
http://wrzucaj.net/tHj
This is only 1/4 of model.

Solver: density-based
Energy: ON
Viscous: standard k-E
Air: Ideal-gas
Boundary conditions:
- pressure inlet: gauge pressure=203990.4 Pa and Temp=1000 K, operating conditions -> pressure=0 Pa
- pressure outlet: gauge pressure=472655.75 Pa and temp=890 K
- symmetry for every wall 'inside'
- wall for outer surface: convection with heat transfer coefficient 58 w/m2-k , free stream temperature=220 K and wall thickness=1 mm

Reference values: compute from: pressure inlet
Flux type: AUSM
Solution Initialization: compute from: pressure inlet


What do you think about that? I've had some troubles and errors like 'backflow' , "time step reduced...' , divergence...
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Old   January 7, 2014, 04:35
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duri
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Quote:
Originally Posted by lotheg View Post
Hello,

Boundary conditions:
- pressure inlet: gauge pressure=203990.4 Pa and Temp=1000 K, operating conditions -> pressure=0 Pa
- pressure outlet: gauge pressure=472655.75 Pa and temp=890 K
Why outlet pressure is more than inlet pressure for nozzle.
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Old   January 7, 2014, 15:44
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Because it is a convergent nozzle. I have written about exhaust nozzle.
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Old   January 11, 2014, 16:11
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Could anyone help? How to model this kind of flow?
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Old   January 19, 2014, 19:14
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Shawn Fotovati
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You could also try pressure based solver. Also try k-w or sst models for turbulence. k-e is more suitable for external flows. double check your mesh and make sure there is no problem with the mesh. Use SIMPLEC.

good luck
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Old   January 20, 2014, 09:19
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Quote:
Originally Posted by sfotovati View Post
You could also try pressure based solver. Also try k-w or sst models for turbulence. k-e is more suitable for external flows. double check your mesh and make sure there is no problem with the mesh. Use SIMPLEC.

good luck
for 0.6 mach and higher speeds denstiy based should prefer to better results.

I didnt understend conditions at outlet. dont u talk about nozzle to air outlet?
if it's like that condition should be like; presure 0 pa and temp 280-290 K.
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