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Old   June 1, 2019, 08:22
Default MRF simpleFoam
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Hi,

I am currently running a steadyState MRF case with a turbine in OpenFOAM 6. I am trying to evaluate the behavior of torque/moment output for different RPM values (defined in MRFProperties) to create a RPM-torque table.

Why do I get the same output torque for different turbine geometries with constant RPM and inlet flow? The case set-up is identical, the only thing that have changed is the number of blades on the turbine.


Is there something I've missed? Thanks for responses in advance!
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Old   June 5, 2019, 04:02
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Lilian Chabannes
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Hello,

Did you properly define the patches where you calculate the forces/moment in controlDict?

Code:
libs
(
"libforces.so" // this is for forces
);

functions
{
    forces{
	type forces;
	functionObjectLibs ("libforces.so");
	patches (BLADE HUB SHROUD); // sum the forces and moments on those patches
	writeControl timeStep;
	writeInterval 1;
	p	p;
	U	U;
	log true;
	rhoInf 1000;
	rho rhoInf;
	CofR (0 0 0); //centreOfRotation
	}
}
Is the MRF zone well defined?
Do you control other parameters to see if the simulation is proper? (does the head, efficiency changes with the flowrate for example)
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mrf, propeller, simplefoma, torque, turbine

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