Steady state Acoustic source contours

arunraj · November 5, 2012, 00:31

Hi all,

I am working on noise reduction in axial flow fan.. I am using FW-H acoustic model for noise prediction... It is an steady state analysis... But during post processing I am not able to find the acoustic source contours to understand from where the noise is actually generating... Is it possible to plot acoustic contours in steady state if I use Broadband noise model instead of FW-H.... It is really difficult to find how much contribution is there due to turbulence,tip vortex for fan noise generation with FW-H....

Jaiganesh S · November 5, 2012, 09:17

Hi Mr. Arun raj,

I am doing Aeroacoustic analysis on aircraft wing using Ansys fluent. After 53 iterations, it getting error. I have mentioned that error below.

Error: Divergence detected in AMG solver: x-momentum.

I have described about my case below.
Pressure based, Transient.
LES Model.
Velocity Inlet , pressure outlet.
Scheme- PISO, neighbor correction - 1, Pressure - standard, momentum - Bounded central differencing, Transient formulation- First order Implicit, non iterative time advancement.
URF for Pressure - 0.001, for Momentum - 0.004.

And also I used Outflow as outlet instead of Pressure outlet. I changed neighbour correction & under relaxation factor. These Changes are not working.

Grid quality details:
Max. cell squish= 9.23091e-001.
Max. aspect ratio = 3.22832e+002.

Kindly help me to solve this problem. I am waiting for your kind response.

Thank you.

arunraj · November 5, 2012, 23:48

Hi,

I havenot worked in transient simulation... But this error seems to be related to your boundary condition...check your boundary condition properly...

Jaiganesh S · November 7, 2012, 07:23

Hi,
Thank you for your kind response. If i use hemi sphere domain instead of rectangular domain, will it solve x momentum error? what is the advantages of hemi sphere domain?

Kindly reply me. Thanks again.

arunraj · November 7, 2012, 07:30

Hi,
I didnt anything related to your domain... It might be related to your mesh...check your mesh quality or bounday condition...I am doing acoustic analyis of axial flow fan...But I am not using any hemispherical domain...

November 5, 2012, 00:31	Steady state Acoustic source contours	#1
arunraj Senior Member Arun raj.S Join Date: Jul 2011 Posts: 212 Rep Power: 16	Hi all, I am working on noise reduction in axial flow fan.. I am using FW-H acoustic model for noise prediction... It is an steady state analysis... But during post processing I am not able to find the acoustic source contours to understand from where the noise is actually generating... Is it possible to plot acoustic contours in steady state if I use Broadband noise model instead of FW-H.... It is really difficult to find how much contribution is there due to turbulence,tip vortex for fan noise generation with FW-H....

November 5, 2012, 09:17	Error: Divergence detected in AMG solver: x-momentum.	#2
Jaiganesh S New Member Jaiganesh S Join Date: Dec 2011 Posts: 8 Rep Power: 15	Hi Mr. Arun raj, I am doing Aeroacoustic analysis on aircraft wing using Ansys fluent. After 53 iterations, it getting error. I have mentioned that error below. Error: Divergence detected in AMG solver: x-momentum. I have described about my case below. Pressure based, Transient. LES Model. Velocity Inlet , pressure outlet. Scheme- PISO, neighbor correction - 1, Pressure - standard, momentum - Bounded central differencing, Transient formulation- First order Implicit, non iterative time advancement. URF for Pressure - 0.001, for Momentum - 0.004. And also I used Outflow as outlet instead of Pressure outlet. I changed neighbour correction & under relaxation factor. These Changes are not working. Grid quality details: Max. cell squish= 9.23091e-001. Max. aspect ratio = 3.22832e+002. Kindly help me to solve this problem. I am waiting for your kind response. Thank you.

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November 5, 2012, 23:48		#3
arunraj Senior Member Arun raj.S Join Date: Jul 2011 Posts: 212 Rep Power: 16	Hi, I havenot worked in transient simulation... But this error seems to be related to your boundary condition...check your boundary condition properly...

November 7, 2012, 07:23		#4
Jaiganesh S New Member Jaiganesh S Join Date: Dec 2011 Posts: 8 Rep Power: 15	Hi, Thank you for your kind response. If i use hemi sphere domain instead of rectangular domain, will it solve x momentum error? what is the advantages of hemi sphere domain? Kindly reply me. Thanks again.

November 7, 2012, 07:30		#5
arunraj Senior Member Arun raj.S Join Date: Jul 2011 Posts: 212 Rep Power: 16	Hi, I didnt anything related to your domain... It might be related to your mesh...check your mesh quality or bounday condition...I am doing acoustic analyis of axial flow fan...But I am not using any hemispherical domain...