Darrieus Wind Turbine - 2d CFD , abnormal results
 

Hello. We are trying to simulate darrieus wind turbine's rotating and find CM values.
But there is a problem. We trying to compare with experimental studies.
In experimental studies, chord lenght 0.265 m, blade height 1.2 m and rotor dia. is 2 meter.
So, in our study, we draw with 2 bades darrieus. Of course, we cant give a height to the blades, because we working 2d.
Okey, we have 300000 mesh, sst k-w, transiet, mesh motion and give radial speed to the ring, others are fixed, and we have 8 m/s inlet wind speed, turbulance indensity 0.5 and lenght scale 0.0265m, blades are moving.
But our results are too high from expected, sometimes too low. We try to catch 0.1 Cm value, because in experimental study Cp is 0.2 and TSR = 2
So, could be an error with our reference values ?
Area = Diameter * Height = 2 m * 1,2 m
Depth = Height, 1,2 m
Lenght = Radius of rotor, 1 m

I checked everything, interfaces, domain properties etc. But i dont understand what is the mistake.. Here is a picture, for 8 hours fluent could solve only for 240 degree, of course blade has to rotate 6-7 tours to be stationary but when i see this, i think it is impossible to catch 0.1 avarage value. It is still solving by the way

Best regards, hope i can find an advice
https://i.hizliresim.com/MVA1Ok.png