[EthanWalker]

Hi,

This is quite a specific issue and I was hoping someone here might have experience or know of something that I could try.

I am using Ansys fluent 17.1 to model a variable pitch vertical axis turbine. Each blade has its own specific rotating domain within an overall turbine rotating domain. I control the pitch of each blade independently by controlling the rotational velocity of each blade domain through the use of a UDF.

my issue is that in the turbine that I am modelling the blades all pitch outwards the whole way round (rotate in the opposite direction of the turbine), the greater the pitch the more I specify the blade domain rotational speed. so I specify the rotational velocity always increasingly negative in rads/s ( eg -0.08 to -6 rad/s)

when I get to the end of the rotation (at 360 degrees azimuth) the rotational velocity/pitch is approximately -6 rad/s, but at the start of the next rotation the pitch is only -4 degrees (approx 0.08 rad/s) this sharp instantaneous drop in rotational velocity causes my model to go unstable (turbulence and velocity unrealistic)

I cannot think of a method where I can reduce the rotational velocity without affecting the pitch angle of the blade.

If anyone has any advise/tips that would be great.

Thanks