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OpenFoam - DynamicMesh SphericalAngularDamper value |
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August 16, 2021, 11:09 |
OpenFoam - DynamicMesh SphericalAngularDamper value
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#1 |
New Member
Join Date: Mar 2021
Posts: 9
Rep Power: 5 |
Hi all,
At the moment I am modelling the efficiency for a hydraulic turbine in OpenFOAM. The generated theoretical power results from the product of angular velocity and torque around the turbine axis. For this purpose I use the dynamic mesh solver sixDoFRigidBodyMotion. From a sensitivity analysis it follows that the sphericalAngularDamper restraint has a large influence on the modelled angular velocity and torque (see attachment). This parameter has the unit [Nms/rad] and represents friction against angular motion. It acts in the opposite direction with respect to the angular motion. The parameter is defined as follows: Code:
restraints { //- Some dumping functions translationDamper { //- Nms/rad // Acts against motion as friction sixDoFRigidBodyMotionRestraint sphericalAngularDamper; coeff 500; } } I hope to hear from you! Best, Bas |
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October 4, 2021, 06:04 |
repl:
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#2 |
New Member
Join Date: Mar 2021
Posts: 9
Rep Power: 5 |
I discovered that there are multiple ways to find optimum operational conditions for a turbine in order to yield maximum production. The first is by running multiple simulations with a forced rotation for various rotational speeds (under a constant flow velocity). The second one is to apply a model with free rotation (and a fixed flow velocity) whilst varying the angular friction coefficient until one finds optimum conditions. Hence, the angular friction coefficient is not a term one knows on beforehand, but one must search for an optimum value that leads to maximum production of the turbine.
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