An Improved Boundary Layer Transition Correlation

Abstract

The influence of pressure gradient and freestream turbulence level on boundary layer transition has been studied experimentally using hot wire instrumentation and digital signal processing and analysis. An established transition correlation and recent transition model were found to give acceptable prediction of the experimental results. The digital system was used to conditionally sample the transitional boundary layer data and hence to determine the mean and fluctuating velocity profiles for the laminar and turbulent parts of the boundary layer separately. The turbulent portions were found to correlate well with fully developed turbulent boundary layer profiles, but the laminar portion profiles deviated considerably from those typical of a laminar boundary layer.