Influence of Stream Turbulence and Pressure Gradient upon Boundary Layer Transition

Abstract

In considering boundary layer transition, the available experimental data and prediction methods are reviewed and further experimental results are presented. Some empirical rules are suggested for the separate effects of stream turbulence and of pressure gradient and of both combined. The approximate nature of these rules is described and the causes indicated.

Investigation of the Laminar-Turbulent Transition of Boundary Layers Disturbed by Wakes

“…Comparisons of the transition obtained by measurements cannot be made to agree with Schlichtings stability theory and new empirical transition criteria such as those of Dunham [13], Hall and Gibbings [14] which take the degree of turbulence in the external flow into account. It was presumed that the disturbances which consist of fluctuations and stochastic turbulence were so large that their influence on the transition can no longer be described by the linear stability theory, which is founded on small perturbations.…”

Effect of sandpaper roughness and stream turbulence on the laminar layer and its transition

“…The coefficients of Equation 9 . (10) where R 6M was set at the asymptotic value obtained by Hall and Gibbings' 10 ' for the smooth plate. It is close to the minimum stability limit.…”

Incompressible flow in contracting ducts

“…Considering the flow at inlet to a contraction, a boundary layer will separate as a laminar layer up to roughly midway through the transition region* 75 '. Assuming a stream turbulence level at inlet of 0-4% then at the start and end of transition R e will have the values of about 940 and 1550< 63 >, so that a laminar separation could occur up to about R eft = 1280. With K { = 0-2 and n = 10 then Rj,, = 5-9 x 10 7 .…”