Wind turbine getting negative torque at high tip speed ratio
 

Good day.

I'm simulating a wind turbine, I designed on my own, using ANSYS FLUENT. At tip speed ratio equal to 5 and lower, I'm getting positive torque. However, at tip speed ratio equal to 6 and above, I'm getting negative torque. Since I have frame motion enabled, the wind turbine is "still spinning in the correct direction", by looking at the vortex visualization by q-criterion, but if this was in the real world, I think, negative torque would mean that the wind turbine is spinning in the opposite direction. I looked at an airfoil pressure contour cut plot and from the looks of it, it seems fine.

Is there something wrong with my simulation? Or does it just simply mean that the design is bad?