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 liping_he May 30, 2012 02:34

torque calculation of impulse turbine

1 Attachment(s)
Dear foamers

I created a case by combining the interDyMFoam (tutorials/multiphase/interDyMFoam/ras/damBreakWithObstacle) and pimpleDyMFoam (tutorials/incompressible/pimpleDyMFoam/propeller) to achieve the simulation of impulse turbine (multiphases flow and AMI). The screenshot of velocity field is shown in attachment containing three nozzles and a runner.
And now, I want to calculate the efficiency. A great issue comes out HOW can i obtain the torque (pressure and viscocity torque ) of runner. I have no idea about this issue. Any advice will be appreciated.

 lovecraft22 May 30, 2012 04:54

Haven't got much of experience on this but… couldn't you just use a force calculation to computer the moment aruond the axis of rotation?

 liping_he May 30, 2012 21:44

Hi,

Now, I dont know how to report force in multiphase case. So i cant obtain torque without force. In singlephase case, the force/torque can be obtained by adding the following code in controlDict
Quote:
 functions { forces { type forces; functionObjectLibs ("libforces.so"); //Lib to load patches (sphere_region0); // change to your patch name rhoName rhoInf; rhoInf 1000; //Reference density for fluid CofR (2 0 0); //Origin for moment calculations outputControl timeStep; outputInterval 1; } forceCoeffs { // rhoInf - reference density // CofR - Centre of rotation // dragDir - Direction of drag coefficient // liftDir - Direction of lift coefficient // pitchAxis - Pitching moment axis // magUinf - free stream velocity magnitude // lRef - reference length // Aref - reference area type forceCoeffs; functionObjectLibs ("libforces.so"); patches (sphere_region0); rhoName rhoInf; rhoInf 1000; CofR (2 0 0); liftDir (0 1 0); dragDir (1 0 0); pitchAxis (0 0 1); magUInf 1e-7; lRef 0.06; // sphere diameter Aref 0.0014137; //1/2 * projected area = pi*r2/2 outputControl timeStep; outputInterval 1; } }
more detail visit:
http://www.cfd-online.com/Forums/ope...es-of15-8.html

regards,
liping

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