cm-history power coefficient in VAWT
 

hi people.. i'm facing with a problem with my 2D unsteady simulation of a VAWT.
i'm having this cm-history (fig 1). it's based on the "reference values":
compute from: the bc of the velocity inlet far away of the turbine
area: my VAWT diameter
length: my VAWT radius

you can see that after a lot revolutions i have a accurate convergence for the cm. in the next figure (fig 2) you can see that every peak its like the other one, so i think the solution its converged.

so, i'm not sure how to calculate the power coefficient. if i take the mean of the cm (cmm) and make: cmm*w (w = angular velocity) i have a bad results. what should i do? :confused:

kinds regards!