Compressor regions

dijiaqiu · January 12, 2017, 09:03

Hello all:

I am a cfx newer. how to isolated the compressor fluid regions. imp and diffuser and volute. two regions or three regions? which type of turbulence model is more appropriate for the centrifugal comperssor?

Best regards

ghorrocks · January 12, 2017, 17:29

If you are asking how to deal with isolated volumes error - then you need to connect the regions with GGIs.

If you are asking how many domains should you use to model your device - that depends on the device, but you need one domain per stator and rotor row.

Turbulence model - My favourite is SST, but k-e is still very popular.

dijiaqiu · January 13, 2017, 02:57

Dear ghorrocks
May I ask why total pressure is very very large near prism layers on the R/S interface, for example, if The value of the Average static pressure outlet is 2bar, the total pressures range is 1bar to 6bar on R/S interface.

ghorrocks · January 14, 2017, 03:33

Please post an image of what you are seeing.

dijiaqiu · January 15, 2017, 20:56

Sorry, i post the image.at the left it's R/S interface. the hub of imp is at the bottom of the image. on the hub of impeller near the R/S interface total perssure is very big 6bar. the BC's pressure is 2.7bar. it's right?

best regard

ghorrocks · January 15, 2017, 22:22

You need to check whether the high total pressure is coming from the statis pressure or the velocity component. You should check static pressure and velocity now.

On the face of it the effect looks like a pressure gradient on the outside wall due to the centripetal acceleration of the fluid.

January 12, 2017, 09:03	Compressor regions	#1
dijiaqiu New Member Join Date: Sep 2011 Posts: 7 Rep Power: 15	Hello all: I am a cfx newer. how to isolated the compressor fluid regions. imp and diffuser and volute. two regions or three regions? which type of turbulence model is more appropriate for the centrifugal comperssor? Best regards

January 12, 2017, 17:29		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,870 Rep Power: 144	If you are asking how to deal with isolated volumes error - then you need to connect the regions with GGIs. If you are asking how many domains should you use to model your device - that depends on the device, but you need one domain per stator and rotor row. Turbulence model - My favourite is SST, but k-e is still very popular.

January 13, 2017, 02:57		#3
dijiaqiu New Member Join Date: Sep 2011 Posts: 7 Rep Power: 15	Dear ghorrocks May I ask why total pressure is very very large near prism layers on the R/S interface, for example, if The value of the Average static pressure outlet is 2bar, the total pressures range is 1bar to 6bar on R/S interface.

January 14, 2017, 03:33		#4
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,870 Rep Power: 144	Please post an image of what you are seeing.

January 15, 2017, 22:22		#6
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,870 Rep Power: 144	You need to check whether the high total pressure is coming from the statis pressure or the velocity component. You should check static pressure and velocity now. On the face of it the effect looks like a pressure gradient on the outside wall due to the centripetal acceleration of the fluid.