Modeling flow from a jet engine

whitestrat13 · November 2, 2014, 18:45

All,

I'm new to these forums. I have been tasked with developing a computational model for a jet engine test cell. I have a model with two bodies, the air in the test cell and the engine itself. I am having issues constraining the model fully. Right now I have successfully defined a two domain interfaces, one for the engine inlet, one for the exit. I have set the interfaces as general connections, and specified mass flow rates. As it stands, air accelerates through the engine and leaves as expected. This model runs successfully.

My issue is that I can't figure out how to have the air come out hotter on the exit side of the engine. I am not concerned with dynamics inside the engine, but the interaction inside the test cell. I have an average outlet temperature, but I can't for the life of me figure out how to get that number into CFX. At some point, after I figure out how to constrain the model with a bulk exit temperature, I will expand the model to have both core and bypass flow through the engine.

Any help you can provide will be much appreciated.

ghorrocks · November 3, 2014, 07:15

Do you know the rate at which heat is being generated? I suspect you can get this easily from the fuel flow rate. Then just apply a heat source term for that many kW in the combustion area of the engine.

whitestrat13 · November 3, 2014, 12:40

We can certainly get the fuel flow information. How would you recommend applying the heat source in the model. Do i constrain it as a wall heat flux, or is there some way to do a volumetric heat source?

The issue is, its ALOT of heat. purely from an M dot delta H approximation, we are talking many megawatts.

whitestrat13 · November 3, 2014, 14:49

I think I may have figured it out. I added a subdomain inside my engine, and defined an energy source. This source was defined by the heat produced from combustion. I appreciate the help.

ghorrocks · November 4, 2014, 07:04

That's is. Define a sub domain and put a volumetric heat source on it. Easy.

November 2, 2014, 18:45	Modeling flow from a jet engine	#1
whitestrat13 New Member Join Date: Nov 2014 Posts: 3 Rep Power: 12	All, I'm new to these forums. I have been tasked with developing a computational model for a jet engine test cell. I have a model with two bodies, the air in the test cell and the engine itself. I am having issues constraining the model fully. Right now I have successfully defined a two domain interfaces, one for the engine inlet, one for the exit. I have set the interfaces as general connections, and specified mass flow rates. As it stands, air accelerates through the engine and leaves as expected. This model runs successfully. My issue is that I can't figure out how to have the air come out hotter on the exit side of the engine. I am not concerned with dynamics inside the engine, but the interaction inside the test cell. I have an average outlet temperature, but I can't for the life of me figure out how to get that number into CFX. At some point, after I figure out how to constrain the model with a bulk exit temperature, I will expand the model to have both core and bypass flow through the engine. Any help you can provide will be much appreciated.

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November 3, 2014, 07:15		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,871 Rep Power: 144	Do you know the rate at which heat is being generated? I suspect you can get this easily from the fuel flow rate. Then just apply a heat source term for that many kW in the combustion area of the engine.

November 3, 2014, 12:40		#3
whitestrat13 New Member Join Date: Nov 2014 Posts: 3 Rep Power: 12	We can certainly get the fuel flow information. How would you recommend applying the heat source in the model. Do i constrain it as a wall heat flux, or is there some way to do a volumetric heat source? The issue is, its ALOT of heat. purely from an M dot delta H approximation, we are talking many megawatts.

November 3, 2014, 14:49		#4
whitestrat13 New Member Join Date: Nov 2014 Posts: 3 Rep Power: 12	I think I may have figured it out. I added a subdomain inside my engine, and defined an energy source. This source was defined by the heat produced from combustion. I appreciate the help.

November 4, 2014, 07:04		#5
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,871 Rep Power: 144	That's is. Define a sub domain and put a volumetric heat source on it. Easy.