The effect of curvature on the transition from laminar to turbulent boundary layer

Clauser, Milton (California Institute of Technology) Clauser, Francis (California Institute of Technology)
naca-tn-613
September 1937


In the flow over the upper surface of a wing, a discrepancy between the predicted and actual point of transition from laminar to turbulent boundary layer was found. This effect may be due to the comparatively small radius of curvature of the upper surface of the wing. Tests were undertaken to investigate this effect. As far as the authors know, the present investigation is the first to show that curvature has a pronounced effect on the transition of the boundary layer from the laminar to the turbulent state. It appears that three important results have been obtained thus far. First, the experimental points for the convex and concave side of the sheet are consistent with each other and, with the experimental accuracy involved, lie on the same curve. Second, this curve can be approximated by a straight line. Third, the order of magnitude of the variation is such that the curvature ordinarily used on the upper surface of an airplane wing might double the critical Reynolds number.

An Adobe Acrobat (PDF) file of the entire report:
http://naca.central.cranfield.ac.uk/reports/1937/naca-tn-613.pdf