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-   -   Problem with torque output from a turbine simulation. (http://www.cfd-online.com/Forums/fluent/91710-problem-torque-output-turbine-simulation.html)

 pa-dundas August 19, 2011 19:52

Problem with torque output from a turbine simulation.

I'm modelling a 5 blade turbine in fluent. The movement of the turbine is shown in the picture below.

http://i524.photobucket.com/albums/c...ivotmotion.jpg

As a blade moves through the lower half of the turbine the blades go parallel to the flow. While the blade is in the upper half of the turbine it is held by a stopper bar so a to allow the blade to spin the turbine and thus generate power. When modellilng the turbine the flow is blocked from the lower half of the turbine so as to simulate how the turbine would react in real life as I knew of no other way to model the pivoting motion of the blades in fluent. The mesh is shown below and also a plot of the velocity magnitude from a simulation with a rotational velocity of 0.6rad/s. Also the left edge is set as a velocity inlet with an velocity of 2m/s.

http://i524.photobucket.com/albums/c...as535/Mesh.jpg

http://i524.photobucket.com/albums/c...ymagnitude.jpg

My problem is that I've set up a cm-monitor to take the torque values for the blades at each time step. I've run the analysis for different rotational speeds varying from 0.1 rad/s to 1.0 rad/s. But as the rotating speed is increased I am also seeing and increase in the torque generated by the turbine when I think I'm supposed to be seeing a decrease in torque as the rotational velocity is increased. Shown below is a screen of the data I am getting. The torque value is that of one full revelution of the turbine.

http://i524.photobucket.com/albums/c...s535/excel.jpg

Does anyone know what I can to to rectify this problem? Any help would be greatly appreciated

 pa-dundas August 21, 2011 09:41

Anyone at all ever have a problem similar to this? I'm really confused as to what I could possibly do to sort this out.

 pa-dundas August 24, 2011 05:43

Anyone at all? If i've left out some information please just ask.

 pa-dundas August 30, 2011 12:25

My thesis is due soon and I could really use some help with this. Even its only something small you think might work to help me get more accurate results on it any advice would be very much appreciated.

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