Acoustic measurements for a supersonic CD nozzle using CFX

Ahmed Dulvi · February 20, 2024, 11:25

I am doing a project on a CD beveled nozzle where I study the jet parameters like core length, deflection etc. along with the noise generated by the jet. But in CFX, I am unable to find any option or input for acoustic measurements.
It would be great if I can get some help on this.

Opaque · February 20, 2024, 13:36

more details?

ghorrocks · February 20, 2024, 16:43

Yes, please provide more details of what you are trying to do - is the acoustic measurement point near or far away? Is the device in a far field environment or are there other objects about? And isn't the acoustic measurements an output from the model, not an input?

Ahmed Dulvi · February 22, 2024, 10:03

"In CFX preprocessor, I'm using SST as turbulence model. What do I need to enable in the preprocessor so that I can get a result related to acoustics, for near and far field?"

ghorrocks · February 22, 2024, 18:10

CFX is a CFD solver, not an acoustics solver. CFX models can generate acoustic fields but the full Navier Stokes equation approach used in CFX is generally very limiting in terms of propagating that out to far field results, or even near field if there are lots of reflections.

If a near field result is all you want then you can do it by running the model and putting a pressure monitoring point at your location. You will then have to extract the pressure vs time history and work out the acoustic properties from that.

If you want far field results or near field with lots of reflections then CFX is unlikely to be manageable. You will need to do a coupled solution between CFX at the noise source and an acoustics simulation code to model the reflections and far field.

February 20, 2024, 11:25	Acoustic measurements for a supersonic CD nozzle using CFX	#1
Ahmed Dulvi New Member Ahmed Dulvi Join Date: Feb 2024 Posts: 2 Rep Power: 0	I am doing a project on a CD beveled nozzle where I study the jet parameters like core length, deflection etc. along with the noise generated by the jet. But in CFX, I am unable to find any option or input for acoustic measurements. It would be great if I can get some help on this.

February 20, 2024, 13:36		#2
Opaque Senior Member Join Date: Jun 2009 Posts: 1,804 Rep Power: 32	more details? __________________ Note: I do not answer CFD questions by PM. CFD questions should be posted on the forum.

February 20, 2024, 16:43		#3
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,703 Rep Power: 143	Yes, please provide more details of what you are trying to do - is the acoustic measurement point near or far away? Is the device in a far field environment or are there other objects about? And isn't the acoustic measurements an output from the model, not an input? __________________ Note: I do not answer CFD questions by PM. CFD questions should be posted on the forum.

February 22, 2024, 18:10		#5
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,703 Rep Power: 143	CFX is a CFD solver, not an acoustics solver. CFX models can generate acoustic fields but the full Navier Stokes equation approach used in CFX is generally very limiting in terms of propagating that out to far field results, or even near field if there are lots of reflections. If a near field result is all you want then you can do it by running the model and putting a pressure monitoring point at your location. You will then have to extract the pressure vs time history and work out the acoustic properties from that. If you want far field results or near field with lots of reflections then CFX is unlikely to be manageable. You will need to do a coupled solution between CFX at the noise source and an acoustics simulation code to model the reflections and far field. __________________ Note: I do not answer CFD questions by PM. CFD questions should be posted on the forum.

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February 22, 2024, 10:03		#4
Ahmed Dulvi New Member Ahmed Dulvi Join Date: Feb 2024 Posts: 2 Rep Power: 0	"In CFX preprocessor, I'm using SST as turbulence model. What do I need to enable in the preprocessor so that I can get a result related to acoustics, for near and far field?"