Vertical Axis Wind Turbine (VAWT)
 

Hi Guys, really hope you can help me. :)

I am working on a 2D based Savonius VAWT which is a drag based torque generation device. My issue is that as I increase tip speed ratio, power generation climbs exponentially to efficiencies above the 59% betz limit, also, literature shows that Savonius VAWTs typically don't have efficiencies higher than 30%.


I am currently using the K-ω SST model as all the journals say this is better for separated flows. My air values are as standard from ansys fluent.

Has anyone got any past experiences with a problem like this?

My task is to optimize the design of a NACA 7715 Savonius VAWT, pitch angle, no. of blades etc. and it will be used in a VAWT cluster later in my studies.

Thanks for any help!! :D