Turbulent Boundary Layer Skin Friction, Heat Transfer and Pressure Measurements on Hypersonic Inlet Compression Surfaces

摘要

An experimental study of turbulent boundary layer flow, under the influence of adverse pressure gradients typical of hypersonic inlets, was conducted on a two-dimensional and an axisymmetric model each instrumented with skin friction, heat transfer and pressure gages. Tests were conducted over a Mach and Reynolds number rage of 6.74 to 11.37 and 1,050,000 per ft. to 29,300,000 per ft., respectively. These test conditions produced boundary layer transition on the forward portions of the models without resorting to artificial trips. It was possible to attain a fully turbulent boundary layer before the start of the adverse pressure gradient region for most of the axisymmetric model tests but for most of the two-dimensional tests, transition was not completed until after the start of the pressure gradient. A comparison of the pressure data with the inviscid pressure distribution was made and good agreement is generally found indicating very little change in effective model shape due to boundary layer growth. This result is a consequence of the large model size relative to the boundary layer thickness, i.e. high Reynolds number flows over large models. An important conclusion resulting from this program was that turbulent boundary layers can negotiate large adverse pressure gradients without separating. Comparison with some existing laminar boundary layer data indicate that a turbulent boundary layer can negotiate adverse pressure gradients at least an order of magnitude greater than those gradients which will separate a laminar layer. (Author)