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-   -   Modeling flow from a jet engine (https://www.cfd-online.com/Forums/cfx/143785-modeling-flow-jet-engine.html)

whitestrat13 November 2, 2014 17:45

Modeling flow from a jet engine
 
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 06:15

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 11:40

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 13:49

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 06:04

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


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