# Resisting torque on a moving mesh

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 January 11, 2010, 19:42 Resisting torque on a moving mesh #1 Member   florian Join Date: Mar 2009 Location: Mannheim - Vincennes - Valenciennes, Deutchland - France Posts: 34 Rep Power: 10 Hi, I am student. For my end of study's project, I try with 2 others students to study a new generation of vertical wind turbine with a CFD simulation . We try to draw the curve of the Power coefficient CP according to lambda (the Tip Speed Ratio). In order to have a reference, I are working in the same time on a Savonius wind turbine. If we had a prototype and a wind tunnel, we would have to connect the wind turbine to a dynamic couple-meter. We would obtain the wished curve by making vary the resisting torque while keeping a constant speed of wind. We started with fluent, but in this software it is not possible to put a resistant torque on a moving mesh. So we made the opposite : we imposed a rotation speed of pales then we measured the couple engendered by the fluid on the rotor. We simulated this with a stationary simulation and a rotational moving mesh boundary condition on blades. And then a in-stationary simulation with a moving mesh. Both simulation give exactly the same results, the residuals are very good, but Cp curve is not realistic for lambda > 0. For Lambda = 0, the result is very close to the theoretical value. After a lot of work we concluded that the model is not good : putting a rotating wind turbine in an air flow and measuring the couple engendered on the tree of rotation is not the same that measuring the rotation speed of a wind turbine on which we impose a resisting torque. I have work on OpenFOAM during an internship period. I have try the mixerVessel2D tutorial. Is it possible to impose a resisting torque on a moving mesh area in OpenFOAM ?? Last edited by floooo; January 12, 2010 at 05:16.

 February 4, 2010, 02:53 #2 New Member   SHIVA Join Date: Feb 2010 Posts: 7 Rep Power: 10 It is possible to feed a Resistive torque and force in fluent for moving mesh model.or otherwise u can use Rigid body solutions (6-dof) Methods in CFX.

 March 14, 2010, 05:59 #3 Senior Member   Herman Join Date: Nov 2009 Posts: 122 Rep Power: 10 Hi floooo I'm also studying a VAWT. Are you sure that resutls obtained using a fixed rotation to the blades is not reasonable? I'm using this approach, and results seems to be good. I have a question for you: I studied the problem using FLUENT, and now I'm trying to use OpenFOAM. I use sliding interface tecnique, but OF torque is not the same of FLUENT one. After a lot of simulation I think that the problem is maybe in boundary conditions. How have you set them for your problem? Thank in advance. Enry.

 March 29, 2010, 20:18 #4 Member   florian Join Date: Mar 2009 Location: Mannheim - Vincennes - Valenciennes, Deutchland - France Posts: 34 Rep Power: 10 Hi enry I think that skshivas gave the solution. But it was too late for my report. Currently I haven't the time to work on it. There is an 6 DOF solver in Fluent. And I think it is possible to solve the problem using and UDF script. I think the Fluent UDF file looks like this: #include "udf.h" DEFINE_SDOF_PROPERTIES(store, prop, dt, time, dtime) { prop[SDOF_MASS] = 10; prop[SDOF_IZZ] = 200.; if (time <= 0.3) { prop[SDOF_LOAD_F_X]=0; prop[SDOF_LOAD_F_Y]=0; prop[SDOF_LOAD_M_Z] = 20.0; } } Florian

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