I am working on the vertical axis wind turbine project. I have attached the picture in 2D.
Wind direction is from negative X to the positive X direction.
I applied 200 rpm in fluent and the rotational axis as (0 0 1) in fluent setup.
I am getting negative moment values when I put moment center as (0 0 0) and moment axis as (0 0 1). but I get the positive moment when I put (0 0 -1) direction.
Moment is a vector which has both magnitude and direction. The question is what is its direction? Answer: The direction of the vector is given by right hand thumb rule. Stretch out the right thumb by folding the remaining 4 fingers. If the direction of rotation is indicated by those 4 folded fingers, the stretched out thumb represents the direction of the vector
The direction of the moment depends on your blade design. From your result I believe your blade design makes the the turbine to rotate in the anti-clockwise direction based on the righthand rule. The reason you're getting a positive moment when you change the moment axis is because you change your sense of direction into the negative z-axis (which is the same as saying -ve moment in the +ve z-axis). If you want to get a positive moment without changing the moment axis, you should change the blade design (just invert it). Hope this helps!
You need to consider the angular momentum produced by the fluid on the turbine or which produced by the turbine on the fluid. Probably is the same situation when you calculate forces created by fluid impinging on surfaces, there are a force and a reaction force.
- Badges
- Science topic