Local measurements of turbulent boundary layer heat transfer on a concave surface using liquid crystals

The goal of the current experiment was to determine whether or not there are large-scale structures visible in the distribution of heat transfer coefficient on a concave surface. The heat transfer measurements were taken using a new technique which uses cholesteric liquid crystals to determine surface temperature, in conjunction with a surface of known heat release per unit area. This technique permits an instantaneous visualization of heat transfer coefficient over a large area. The response rate of the package is high enough to include the important dynamics of the transport processes. A mixing length model for concave curvature was applied to STAN5, an existing, finite-difference computer program. This model is shown to successfully predict mean heat transfer rates in concavely curved turbulent boundary layers. It was shown that the outer-layer mixing length distribution was not an important variable in predicting heat transfer rates for water (Pr = 5).