how to set up high temperature gas turbine flow simulation?

adam2008 · July 22, 2009, 17:48

hi,
I just started a gas turbine simulation with CFX. The typical air flow temperature is 2000F and some places will have much cooler temperature because I also modeled some cooling holes. Now my question is mainly related to how to setup fluid flow material properties.
The default setup of Air Ideal Gas in CFX has constant Cp, viscosity (mu) and thermal conductivity (k). Looks like those Cp, mu and k are all values when air is at 25C and 1atm. However, realistically Cp, mu and k all change as increasing temperature.
Since my simulation deals with high T gas flow with large temperature variance, does that mean I must input proper Cp, mu and k as a function of T in material setup? I saw we can input Cp, mu and k through NASA format, sutherland law etc. In my case, do I really have to input those parameters to setup a T dependent Cp/mu/k function?

Thanks a lot for any advice.

ghorrocks · July 22, 2009, 19:33

Hi,

Whether it is significant or not is up to you to determine. Run a model with and without variable properties and see if the difference is significant in your case.

You may also find that an ideal gas is not accurate either. You may have to look into the real gas properties. It all depends on how accurate you want to be.

Glenn Horrocks

July 22, 2009, 17:48	how to set up high temperature gas turbine flow simulation?	#1
adam2008 New Member Join Date: Jul 2009 Posts: 25 Rep Power: 17	hi, I just started a gas turbine simulation with CFX. The typical air flow temperature is 2000F and some places will have much cooler temperature because I also modeled some cooling holes. Now my question is mainly related to how to setup fluid flow material properties. The default setup of Air Ideal Gas in CFX has constant Cp, viscosity (mu) and thermal conductivity (k). Looks like those Cp, mu and k are all values when air is at 25C and 1atm. However, realistically Cp, mu and k all change as increasing temperature. Since my simulation deals with high T gas flow with large temperature variance, does that mean I must input proper Cp, mu and k as a function of T in material setup? I saw we can input Cp, mu and k through NASA format, sutherland law etc. In my case, do I really have to input those parameters to setup a T dependent Cp/mu/k function? Thanks a lot for any advice.

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July 22, 2009, 19:33		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,870 Rep Power: 144	Hi, Whether it is significant or not is up to you to determine. Run a model with and without variable properties and see if the difference is significant in your case. You may also find that an ideal gas is not accurate either. You may have to look into the real gas properties. It all depends on how accurate you want to be. Glenn Horrocks