A Conservation-Law Approach to Predicting the Length of the Boundary Layer Transition Region

Abstract

The length of the boundary layer transition region is predicted by the conservation of momentum, based on the prediction method of the boundary layer transition by the mass conservation. The predicted length decreased in line with wall cooling and an increase of Mach number. Some calculated lengths agreed with experimental results, and others did not. To examine the insufficient agreement, the effect of the wall temperature on the length is discussed. Under the heated-upstream wall condition, which may appear in hypersonic wind tunnel experiments, the length of the transition region and the transition Reynolds number increased in line with the wall cooling in the prediction calculation. Most of the experimental data are in the region between the calculated results with this heated-upstream wall condition and those with the uniform wall-temperature condition. The similarity of the results predicted by the energy conservation to those predicted by the momentum conservation is also discussed.