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Old   August 28, 2012, 10:34
Default RAE2822 transonic aerofoil
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Alexandru Stroe
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Hi. I am currently trying to simulate the flow over a rae2822 aerofoil. This is a transonic flow and from what I've read in the forum one of the suggested solvers is sonicFoam. The mesh was build using gmsh and I've adapted the data in the 0 folder to best suit my configuration. The initial conditions are found http://www.grc.nasa.gov/WWW/wind/valid/raetaf/raetaf04/raetaf04.html . The problem is that my Cp pressure distribution is nothing near of the original experiment results. I have attached my 0, system and constant folder if this could help. Also i attached a chart of the distribution of the pressure. Thank you in advance
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Old   January 28, 2013, 13:57
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After much stress and searching around and help from others i got my simulation to work. The results are almost the same as other RAE2822 experiments, the only problem is that the shock is not where it is supposed to be. I attached a picture for reference. If anyone needs the case files, i will post them here. Also if you got any ideas about the shock, feel free to share them.
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Old   May 22, 2013, 13:55
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I suspect a discrepancy between the case described in the NASA website
http://www.grc.nasa.gov/WWW/wind/val.../raetaf04.html
and the wind tunnel study. The boundary conditions (Mach 0.729, alpha = 2.31 degrees) seems not to correspond to any experimental results in the AGARD report.

Please see case #6 in the table on page 191 of:
Cook, P.H., M.A. McDonald, M.C.P. Firmin, "Aerofoil RAE 2822 - Pressure Distributions, and Boundary Layer and Wake Measurements," Experimental Data Base for Computer Program Assessment, AGARD Report AR 138, 1979.

(I do not recall where I downloaded the report some years ago....)

The boundary conditions on the another part of the NASA website do seem to match case #6 in the AGARD report.
http://www.grc.nasa.gov/WWW/wind/val...af/raetaf.html

Mach 0.725, alpha = 2.92 degrees

Good luck; I don't know if you are still checking this forum, but I hope this helps others who are doing validation.

- Corretelli
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Old   May 23, 2013, 05:05
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Indeed, the boundary conditions are different. I will simulate with the new values and maybe i will get an improvement. Thank you for your observations.
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Old   May 27, 2013, 09:40
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Ilya
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Quote:
Originally Posted by icedevill View Post
Indeed, the boundary conditions are different. I will simulate with the new values and maybe i will get an improvement. Thank you for your observations.
Hi.

I wait for your further simulations. I do airfoil at M>>0.3 too but it's NACA 23012 and i really interesting about your results.

But i have several questions about your case cause i didn't see mesh (there is empty polyMesh in the archive).

Which size is your domain?

It seems that you have small simulation time, so the solution is not "stationary".
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Old   May 27, 2013, 10:04
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I will attach an archive with what i did so far. The mesh was build using airfoilmesh2, a python script created by someone. The lengths of the domain, specified in the input script are:

-10 X_back control domain
5 X_front control domain
-5 Y_down control domain
5 Y_up control domain .

About the time: The deltaT in my controlDict file was the biggest i could find without crushing my simulation with an error. From what i read, finding the right deltaT is a matter of trial and error. Currently it is 4e-08, if i were to push it to 4e-07 for example, the simulation would crush. As a physical time i let it run for a couple of days as a single processor case.

Right now i am a bit caught between work and writing my dissertation, but i hope i will come with the new simulation results soon.

The archive is http://www.megafileupload.com/en/fil...e-diz-zip.html
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Old   May 28, 2013, 04:35
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Quote:
Originally Posted by icedevill View Post
-10 X_back control domain
5 X_front control domain
-5 Y_down control domain
5 Y_up control domain .

About the time: The deltaT in my controlDict file was the biggest i could find without crushing my simulation with an error. From what i read, finding the right deltaT is a matter of trial and error. Currently it is 4e-08, if i were to push it to 4e-07 for example, the simulation would crush. As a physical time i let it run for a couple of days as a single processor case.
I mean endTime of your simulation, not timeStep.

If you have domain size about 15 m, and U approx 240 m/s, you need endTime approx 0.06. But i think it would be better to set 0.12 or higher just wait till Cx or Cy becomes constant.
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Old   May 28, 2013, 05:55
Default NACA 23012 results, transonic flow
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What i've got about my airfoil (exp and Fluent data were extracted from article, but it's in russian. originally exp data from TZAGI report)

M06_rhocentral.jpg

So there present oscillations, they were caused by second order schemes. I'll simulate it on upwind later.

The differences in p fields are showed here:

upwind
firstOrder.jpg

linear limited 1
secondOrd.jpg

also i will share my results obtained with sonicFoam, but later
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Old   December 16, 2014, 04:19
Default RAE 2822 - Experimental measures
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Pierluigi Rossi
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Dear all,

can someone send to me the following technical memorandum:

Cook, P.H., M.A. McDonald, M.C.P. Firmin, "Aerofoil RAE 2822 - Pressure Distributions, and Boundary Layer and Wake Measurements," Experimental Data Base for Computer Program Assessment, AGARD Report AR 138, 1979.

My email address follows:
kevin.kurany89@gmail.com

Thanks in advance.
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