Help pls! Transpiration cooling

z3r0 · February 22, 2010, 15:59

Hi there

I'm new here and I'm making this thread as the title says - for help.

I'm trying to model transpiration cooling process within combustion chamber walls. There is a hot gas section between two porous walls. The hot gases velocity at inlet is about 50 m/s and their temperature about 1800K. Over the higher wall and under the lower wall there are two cooling air sections (velocity=13 m/s, temp=573.15K). There is a pressure difference between the sections which should be about 0.1 atm.

The problem is - when I'm increasing the porosity of the walls - the wall temperature on the hot gases side is increasing and I think it should act in the opposite way :/

Does anyone have any idea why doeas it act like that?

I need to make this application for my engineer diplom so the case is pretty urgent.

Thank You for any usefull responses.

z3r0 · February 24, 2010, 03:19

OK - so after including radiation model it is better - the temperature of porous wall is lower than the temperature of the solid wall but still - with increasing porosity, temperature of the wall on the hot gases side is increasing to... Can anyone tell me why it's like that and what to do to change it?

February 22, 2010, 15:59	Help pls! Transpiration cooling	#1
z3r0 New Member Karol Join Date: Feb 2010 Posts: 2 Rep Power: 0	Hi there I'm new here and I'm making this thread as the title says - for help. I'm trying to model transpiration cooling process within combustion chamber walls. There is a hot gas section between two porous walls. The hot gases velocity at inlet is about 50 m/s and their temperature about 1800K. Over the higher wall and under the lower wall there are two cooling air sections (velocity=13 m/s, temp=573.15K). There is a pressure difference between the sections which should be about 0.1 atm. The problem is - when I'm increasing the porosity of the walls - the wall temperature on the hot gases side is increasing and I think it should act in the opposite way :/ Does anyone have any idea why doeas it act like that? I need to make this application for my engineer diplom so the case is pretty urgent. Thank You for any usefull responses.

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February 24, 2010, 03:19		#2
z3r0 New Member Karol Join Date: Feb 2010 Posts: 2 Rep Power: 0	OK - so after including radiation model it is better - the temperature of porous wall is lower than the temperature of the solid wall but still - with increasing porosity, temperature of the wall on the hot gases side is increasing to... Can anyone tell me why it's like that and what to do to change it?