Cold FLow analysis in Gas Turbine..Help Needed

juzer_700 · May 18, 2012, 07:45

I have been trying to use ANSYS FLUENT Software to simulate cold flow analysis inside a combustion chamber. But I am having difficulties. It shows reverse flow when I run the calculation. My geometry is in 2D-Axisymmetrical. Also I have taken a swirl facter of 0.7 using K-Epsilon RNG turbulence method.

Inlet condition:
Velocity- 1m/s, Air at 600K
Pressure Outlet - Gauge pressure=0

Is the reverse flow because I have included the swirl in the flow? Or is it because my domain is small?

I would really appreciate if you can help me figure out the problem. Thanks in advance.

jwillie2000 · May 23, 2012, 05:18

Hi, I think it is because of the swirl in the flow. I would suggest you activate the radial equilibrium pressure distribution option at the outlet and allow sufficient time for it to run and see whether the reverse flow would go away. Good luck! Jimmy

foamcfd · May 23, 2012, 06:18

It could be physical because of the swirl. Try extending your doamin at outlet. I won't worry if it's physical though.

juzer_700 · May 23, 2012, 07:28

@foamcd @jwillie2000

Thanks for replying

I extended the domain. And also activated the radial equilibrium pressure. Although the reversed flow has reduced, but there are still one or two points where it's occuring. I think it's physical as you pointed out.

JAY ADHVARYU · August 17, 2013, 12:11

How i get mean quatity plot in fluent like mean pressure plot, mean stremline plot etc.

jwillie2000 · August 17, 2013, 14:52

Hello,

You have to monitored the quantities you are referring to. Normally u would do it in a plane if it is a 3D problem and you can take the area weighted average of the said quantity and then do the plot after. Are u running unsteady simulation? I would assume yes. In case you want to know what is happening along the centerline you can also export the data if you define your centerline. Once the data is exported as ASCII data you can do the plot using any plotting program.

You need to be more specific about what you want to do in case my post doesn't answer your question.

JAY ADHVARYU · August 24, 2013, 10:42

I have some problem with my boundary condition that how i utilize the neumann condition(∂φ/∂x = 0) at outlet. Can i select pressure outlet at outlet?
my inlet condition is :
flat velocity profile =40m/s
Re=1.916*10^5
turbulent intensity=4.5%
And Inlet height of duct=5mm

I select velocity inlet at inlet because my flow is incompresible.
And axis boundary condition applied along the centerline.
and no slip condition at wall.

pls help me.

raymond350 · September 10, 2013, 06:03

Your inlet velocity is just 1m/s? If you increase it to say 30 or 40m/s i believe you will have lesser or no reverse flow.

JAY ADHVARYU · September 30, 2013, 03:47

yes, my flow is fully developed if you able to help pls help me as fast as possible because if i use pressure outlet at outlet i got reverse flow.

May 18, 2012, 07:45	Cold FLow analysis in Gas Turbine..Help Needed	#1
juzer_700 Member Join Date: Apr 2012 Location: Mainz, Germany Posts: 60 Rep Power: 14	I have been trying to use ANSYS FLUENT Software to simulate cold flow analysis inside a combustion chamber. But I am having difficulties. It shows reverse flow when I run the calculation. My geometry is in 2D-Axisymmetrical. Also I have taken a swirl facter of 0.7 using K-Epsilon RNG turbulence method. Inlet condition: Velocity- 1m/s, Air at 600K Pressure Outlet - Gauge pressure=0 Is the reverse flow because I have included the swirl in the flow? Or is it because my domain is small? I would really appreciate if you can help me figure out the problem. Thanks in advance.

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May 23, 2012, 05:18		#2
jwillie2000 Member James Willie Join Date: Mar 2009 Posts: 81 Rep Power: 17	Hi, I think it is because of the swirl in the flow. I would suggest you activate the radial equilibrium pressure distribution option at the outlet and allow sufficient time for it to run and see whether the reverse flow would go away. Good luck! Jimmy

May 23, 2012, 06:18		#3
foamcfd New Member Yogesh Patil Join Date: Nov 2009 Posts: 20 Rep Power: 17	It could be physical because of the swirl. Try extending your doamin at outlet. I won't worry if it's physical though.

May 23, 2012, 07:28		#4
juzer_700 Member Join Date: Apr 2012 Location: Mainz, Germany Posts: 60 Rep Power: 14	@foamcd @jwillie2000 Thanks for replying I extended the domain. And also activated the radial equilibrium pressure. Although the reversed flow has reduced, but there are still one or two points where it's occuring. I think it's physical as you pointed out.

August 17, 2013, 12:11		#5
JAY ADHVARYU New Member JAY Join Date: Jul 2013 Posts: 10 Rep Power: 13	How i get mean quatity plot in fluent like mean pressure plot, mean stremline plot etc.

August 17, 2013, 14:52		#6
jwillie2000 Member James Willie Join Date: Mar 2009 Posts: 81 Rep Power: 17	Hello, You have to monitored the quantities you are referring to. Normally u would do it in a plane if it is a 3D problem and you can take the area weighted average of the said quantity and then do the plot after. Are u running unsteady simulation? I would assume yes. In case you want to know what is happening along the centerline you can also export the data if you define your centerline. Once the data is exported as ASCII data you can do the plot using any plotting program. You need to be more specific about what you want to do in case my post doesn't answer your question.

August 24, 2013, 10:42		#7
JAY ADHVARYU New Member JAY Join Date: Jul 2013 Posts: 10 Rep Power: 13	I have some problem with my boundary condition that how i utilize the neumann condition(∂φ/∂x = 0) at outlet. Can i select pressure outlet at outlet? my inlet condition is : flat velocity profile =40m/s Re=1.916*10^5 turbulent intensity=4.5% And Inlet height of duct=5mm I select velocity inlet at inlet because my flow is incompresible. And axis boundary condition applied along the centerline. and no slip condition at wall. pls help me.

September 10, 2013, 06:03		#8
raymond350 New Member Join Date: Feb 2012 Posts: 18 Rep Power: 14	Your inlet velocity is just 1m/s? If you increase it to say 30 or 40m/s i believe you will have lesser or no reverse flow.

September 30, 2013, 03:47		#9
JAY ADHVARYU New Member JAY Join Date: Jul 2013 Posts: 10 Rep Power: 13	yes, my flow is fully developed if you able to help pls help me as fast as possible because if i use pressure outlet at outlet i got reverse flow.