laminar boundary layer on vehicle scale model testing?

[rberns2]

Hello,
if vehicle scale model wind tunnel testing is conducted, is it possible to have laminar boundary layers at all or will they always be turbulent due to the high reynolds numbers? (except just beyond stagnation points). Up to which Reynolds number (roughly) they will be laminar?
Thanks,

Rene

 

[reidh]

I don't have exact numbers for you, but it is possible to have a laminar boundary layer on scale models. I will check to see if I have any old test reports on Monday that may have Re numbers listed.

-Reidh

 

[rberns2]

Thanks, that would really be helpfull. Any idea whether the change from laminar to turbulent occurs around 1e6 Reynolds and that's the only reason for a drop in cd, or are there further reasons to that (optimum edge radii)?