WT_Perf convergence with increasing number of blade elements

Hi all,

did someone try to check the results sensibility with the blade elements number when using WT_Perf?
I mean, how can I know how many elements I should use. I have to perform a convergence analysis or there is a value of reference, an advised one for every blade length.
I considered 9 elements of 4 meters span each and a tip element of 2 meters width, but this choice was arbitrary.
This number is also related to how much the blade characteristics change along the blade axis (example, strongly tapered blade)?



Hi Marco,

When using hub and tip loss models, I think it is good to use a higher density of elements near the hub and tip since the aerodynamic loading is changing most rapidly in these regions. I like to use cosine spacing to define the blade segments, which gives smaller (more densely packed) elements at the hub and tip. I am not aware of any hard rules to select the number of segments, but I think having at least a few elements in the inner and outer 5-10% of the blade is a good idea.

Danny Sale
University of Washington
Mechanical Engineering

I agree with Danny.