# Nozzle of turbojet engine

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 January 6, 2014, 17:18 Nozzle of turbojet engine #1 New Member   KK Join Date: Jan 2014 Posts: 3 Rep Power: 5 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...

January 7, 2014, 04:35
#2
Senior Member

duri
Join Date: May 2010
Posts: 160
Rep Power: 9
Quote:
 Originally Posted by lotheg 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.

 January 7, 2014, 15:44 #3 New Member   KK Join Date: Jan 2014 Posts: 3 Rep Power: 5 Because it is a convergent nozzle. I have written about exhaust nozzle.

 January 11, 2014, 16:11 #4 New Member   KK Join Date: Jan 2014 Posts: 3 Rep Power: 5 Could anyone help? How to model this kind of flow?

 January 19, 2014, 19:14 #5 Member   Shawn Fotovati Join Date: Jul 2009 Location: Cincinnati, OH Posts: 42 Rep Power: 10 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

January 20, 2014, 09:19
#6
New Member

ugurcan gördük
Join Date: Aug 2012
Location: Turkey
Posts: 4
Rep Power: 7
Quote:
 Originally Posted by sfotovati 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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