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Rotor 37 problem

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Old   October 29, 2013, 13:31
Default Rotor 37 problem
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Paul
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Hello,

I am doing a rotor 37 simulation of a single blade passage with periodic BC using openfoam 2.2, i am not able to figure out which solver to use. Currently i m using rhoPorousMRFSimpleFoam.
I am not able to get any results, negligible flow is going inside the main domain .Can anyone guide me how to do this. I read somewhere that you have to develop a compressor map by changing the back pressure. How to do that ??

rpm of rotor is = 12465
My boundary conditions are:
-------------------------------------------------------------------------
p

Code:
dimensions      [ 1 -1 -2 0 0 0 0 ];

internalField   uniform  349300;

boundaryField
{
    Blade
    {
        type            zeroGradient;
    }
    Inlet
    {    
          
        type            totalPressure;
       p0              uniform 342000;
           value           uniform  349300;
        U               U;
        phi             phi;
        gamma           1.40;
        rho             rho;
        psi             none;
    }
    Outlet
    { 
      type                fixedValue;
      value               uniform  349300;
    }
    Shroud
    {
         type           zeroGradient;
    }
    Hub
    {
         type           zeroGradient;
    }
  periodic_upper
    {
        type            cyclic;
    }
    periodic_lower
    {
        type            cyclic;
    }
}
--------------------------------------------------------------------------
U
Code:
dimensions      [ 0 1 -1 0 0 0 0 ];

internalField   uniform (1 1 0);

boundaryField
{
    Blade
    {
        type            fixedValue;
        value           uniform (0 0 0);
    }
    Inlet
    {
       type            pressureDirectedInletVelocity;
       inletDirection  uniform (0.9975 0.0704 0);
       value           uniform (0 0 0);
    }
    Outlet
    {
        type            inletOutlet;
        inletValue      $internalField;
        value           $internalField;
    }
    Shroud
    {
         type            fixedValue;
        value           uniform (0 0 0);
    }
    Hub
    {
         type           fixedValue;
        value           uniform (0 0 0);
    }
  periodic_upper
    {
        type            cyclic;
    }
    periodic_lower
    {
        type            cyclic;
    }
}
-------------------------------------------------------------------------
T
Code:
dimensions      [ 0 0 0 1 0 0 0 ];

internalField   uniform 482.94;

boundaryField
{
    Blade
    {
        type            zeroGradient;
    }
    Inlet
    {
        type            totalTemperature;
        T0              uniform 500.5;
        value           uniform 500.5;
        gamma           1.4;
        phi             phi; 
        psi             thermo:psi;
    }
    Outlet
    {
        type            zeroGradient;
    }
       Shroud
    {
         type            zeroGradient;
    }
    Hub
    {
         type           zeroGradient;
    }
   periodic_upper
    {
        type            cyclic;
    }
    periodic_lower
    {
        type            cyclic;
    }
}
--------------------------------------------------------------------------

Thanks a lot !!

Last edited by wyldckat; November 1, 2013 at 20:01. Reason: Added [CODE][/CODE]
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Old   November 1, 2013, 20:08
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Bruno Santos
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Greetings Paul and welcome to the forum!

I've gotten the private message you sent me.
Quote:
Originally Posted by S.N.Paul View Post
I am doing a rotor 37 simulation of a single blade passage with periodic BC using openfoam 2.2, i am not able to figure out which solver to use. Currently i m using rhoPorousMRFSimpleFoam.
I have no clue what a "rotor 37" is. Do you have any good online links on this topic?

Quote:
Originally Posted by S.N.Paul View Post
I am not able to get any results, negligible flow is going inside the main domain .Can anyone guide me how to do this. I read somewhere that you have to develop a compressor map by changing the back pressure. How to do that ??
Honestly, I think you're trying to solve waaaay too many problems in a single step.
My advice: step back and take a simpler look into the problem you're trying to solve. In other words: use the strategy to divide and conquer.

So, the basic questions are:
  1. In essence, what exactly are you trying to simulate? I ask this from a point of view of ignoring all of the specific details.
  2. What results to you need to extract from the simulation?
Best regards,
Bruno
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Old   November 2, 2013, 14:07
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Paul
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Hello Bruno,

Thanks for your reply
The NASA rotor 37 is an isolated transonic axial compressor rotor with 36 blades.
So instead of the whole rotor, i am simulating a single blade with periodic boundary conditions. So my domain consists of (inlet, outlet, hub shroud and a single blade)

I have the results from some other software, i just want to validate them using openfoam using the same BC.
So now any suggestions !!
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Old   November 2, 2013, 16:36
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Hi Paul,

Transonic? That's a big jump, at least for me, given my level of experience on this.

The best I can do is to suggest the following (and since you're using OpenFOAM 2.2):
  1. The tutorial "incompressible/SRFSimpleFoam/mixer" has got a very simple geometry, with a 1/4th part of a mixer. It's designed for SRF, but it can be easily be modified to MRF and it's 3D.
  2. Then there is is the tutorial "incompressible/simpleFoam/mixerVessel2D", which exemplifies how to set-up an MRF case, but it's 2D.
  3. As for a solver, there are a few options that come to mind, but these are somewhat basic:
    • rhoPimpleFoam
    • rhoCentralFoam
    • sonicFoam
    A description for each one is given here: http://www.openfoam.com/features/standard-solvers.php
    In theory, it shouldn't be necessary to use a solver whose name has got MRF in its name, but I'm not certain if all of them are "fvOptions" ready
  4. As for your boundary conditions, now I'm getting a clearer picture:
    1. The U field seems to have a wrong BC for it. It should be something like this:
      Code:
          outlet
          {
              type            inletOutlet;
              inletValue      uniform (0 0 0);
              value           uniform (0 0 0);
          }
    2. The pressure BC... I have no idea if the "waveTransmissive" BC should or should not be used on the outlet. You can find out some more information about each boundary condition from here: http://www.openfoam.org/docs/cpp/
Beyond this, I can only hope that someone more experienced on this can answer.

Best regards,
Bruno
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Old   November 26, 2013, 06:44
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Mahdi S
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I think you might finally end up with "sonicFoam" because NASA rotor 37
is a transonic rotor and you need to consider compressibility and turbulence for that. "sonicFoam" provides these issues for you, however you need to make a decision whether you should have mesh motion or not. in this case "sonicDyMFoam" could be a try.
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