Feasibility of flight experiments and instrumentation hardware for in-flight hypersonic boundary-layer measurements

摘要

We have examined the feasibility of implementing nonintrusive optical diagnostics to measure the properties of the boundary layer surrounding a hypersonic vehicle. Measurements of density, temperature, location of the shock front, and N2, O2, and NO concentrations are feasible using electron-beam fluorescence, for which instrumentation appropriate for flight experiments already exists. In particular, NO will be a key indicator of the chemistry occurring at the vehicle nose and leading edges. Measurements of velocity and O2 and NO concentrations will be feasible using laser-induced fluorescence when rugged and reliable miniature UV laser sources become available; such laser sources should be developed in the next few years. Optical and sensor instrumentation for spectrally resolving the fluorescence along a line emanating from the vehicle and passing radially through the shock front is presently available. Laboratory and wind tunnel experiments will be required to develop the technology base needed to apply these advanced diagnostics. Nevertheless, experimental data acquired from these diagnostic methods, both in flight experiments and in wind tunnel tests, will be invaluable for validating computational fluid dynamics computer codes and for designing next-generation high-performance hypersonic flight vehicles.