CL and CDi comparison @ different Re

Gordon McCutcheon

Hi there, I have conducted an analysis on a NACA0015 wing using PIV in PTV mode to obtain the flow field characteristics. The freestream velocity is 20m/s giving a Reynolds number of 200,000. The paper used for comparison performed the same experiment but with pressure probes with the wing being a NACA0016. Freestream velocity was 60 m/s which gives a Reynolds number of 1.27 million.

The main question is:

How valid is our comparison of CDi and CL with this other papers results? I am getting very similar values! How much error, if any, is there in my method?

I know that at the higher Re # transition will occur on the wing whereas after testing for transition on our wing I found that the flow was very laminar till near the trailing edge.

I am using equations derived by BETZ and MASKELL in order to obtain the induced drag and Prandtl's lifting line theory for the lift.

your sincerely

Gordon (Final year PhD student)