CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Main CFD Forum

Aeroacustic problem in Automotive field

Register Blogs Members List Search Today's Posts Mark Forums Read

Reply
 
LinkBack Thread Tools Display Modes
Old   November 6, 2001, 06:48
Default Aeroacustic problem in Automotive field
  #1
Gabriele Velenich
Guest
 
Posts: n/a
Do you know any SOFTWARE to be able to solve aeroacustic problem in Automotive field like this: how I investigate pressure fluctuations generated by unsteady hydrodynamic flow structures on the vehicle surface that are a source of wind-generated noise? How can evaluate noise and buffeting problems for the "spider" car. I have found on the web a paper with PowerFlow about this problem. Can you send me further information?

Yours sincerely

Gabriele Vèlenich

  Reply With Quote

Old   November 7, 2001, 04:28
Default Re: Aeroacustic problem in Automotive field
  #2
Helge
Guest
 
Posts: n/a
1) Aeroacoustic is one of the remaining big problems in CFD. But some steps are done. 2) STAR-CD offers a tool which claims to be able to do such analyses. But as far as I know this tool is "only" a post processing tool which generates pressure fluctuations based on the calculated turbulence field. May be this is sufficient to solve engineering problems like the reduction of buffeting. 3) Powerflow also claims to be able to solve aeroacoustic problems. This is due to the fact that powerflow in general only performs time dependent simulations with a very small time step. For the buffeting problem that is may be enough because you can expect frequencies lower then 100 Hz. But even for this frequency you should use a time step lower then 1/600 sec 4) In any case the results strongly depend on the ability of the code to solve for the turbulence in the flow field and this is as you know also one of the big problems in CFD 5) to sum up: with lots of experience in CFD connected with experimentation you may be able to judge wether one geometry is better then another due to noise generation. But you should not expect to get exact results of frequencies or noise levels
  Reply With Quote

Old   November 7, 2001, 05:19
Default Re: Aeroacustic problem in Automotive field
  #3
Smith
Guest
 
Posts: n/a
In general, there are 2 big issues in computational aeroacoustics, one is the acurate temporal and spatial resolution of the source terms - you need a lot of mesh and you need to run with very small timesteps.

The other is the propagation of those sources to the far field where they are heard by the 'observer'. This can be done either directly (i.e mesh the far field => even more mesh!) or analyticaly using something like Ffowcs-Williams/Hawkins version of Lighthill's acoustic analogy (lots of net references for this).

In most problems the noise energy is a very small percentage of the total (say 1-2%) so if your flow solution contains a couple of % error your noise prediction will be completely wrong.
  Reply With Quote

Old   November 7, 2001, 07:16
Default Re: Aeroacustic problem in Automotive field
  #4
Dimitri Nicolopoulos
Guest
 
Posts: n/a
Our software RADIOSS-CFD is mostly used for aeroacoustic numerical simulations. RADIOSS-CFD ios a FE code that solves the NS equations (LES turbulence) fully coupled with the structure in the time domain (explicit time integrator). We provide boundaries with prescribed acoustic impedance as well. So far, the code has been used successfully for problems like exhausts, intakes, centrifugal and axial fans, side mirrors and generally speaking components. Full car simulations require *lots* of CPU ressources. You can check our website for examples and published papers: www.mcube.fr

Dimitri Nicolopoulos
  Reply With Quote

Old   November 7, 2001, 14:25
Default PAM-FLOW
  #5
Kosala W.
Guest
 
Posts: n/a
Dear Gabriele,

PAM-FLOW from ESI Group is a finite element based explicit solver that is used extensively for aeroacoustics simulations within the automotive industry. PAM-FLOW can handle both low frequency and high frequency phenomena.

Proven automotive applications include sunroof and side window buffeting, wind rush noise due to side mirrors, A-pillar, wipers, roof-racks etc., and internal components such as intake manifolds, engine cooling fans and HVAC systems.

We provide an integrated auto-mesher that facilitates boundary layer meshing, even for ultra-complex geometries. CPU requirements are addressed by highly scalable parallel solvers.

Please visit our website (www.esi-group.com) or contact me for additional details.

Best Regards Kosala Wickramasinghe ESI North America kwickr@esidetroit.com www.esi-group.com
  Reply With Quote

Old   December 11, 2001, 04:43
Default Re: Aeroacustic problem in Automotive field
  #6
Bipin
Guest
 
Posts: n/a
Hi,

The Fluent6.0 version would be able to do aero-acoustic modeling. This can be done through use of udf built by FLuent.

Lighthill-Curle analogy is used for noise computation in which it was not necessary to have grid upto the observers point.

The code has been verified for simulating noise due to flow over a

1. Flat plate 2. 2D cylinder.

For both the cases the results were in GOOD aggrement with the experimental one. Both the sound generated and dominant shedding frequency was claculated in close aggrement(St. Number was 0.191 for Fluent & 0.186 for Experiment).

However, this was done using LES for modeling flow. The noise prediction would be directly depending upon the prediction of pressure values.

The overall code is very easy to use and had been demonstrated to customers like GM.

Bipin
  Reply With Quote

Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
execFlowFunctionObjects - unknown field problem Toorop OpenFOAM Post-Processing 8 May 26, 2015 08:27
Gambit - meshing over airfoil wrapping (?) problem JFDC FLUENT 1 July 11, 2011 05:59
IcoLagrangianFoam problem in contiuation run amp field reading from input stream gschaider OpenFOAM Running, Solving & CFD 2 May 27, 2008 03:45
Phase locked average in run time panara OpenFOAM 2 February 20, 2008 15:37
pressure field problem. michal FLUENT 1 March 18, 2004 15:45


All times are GMT -4. The time now is 15:52.