Advanced Reentry Aeromechanics

Abstract : This report summarizes the results of a research program that addressed various aspects of hypersonic reentry vehicle design technology. A second-order turbulent closure model was extended to the prediction of boundary layer transition. The existing wind tunnel measurements of roughness-dominated nosetip transition were analyzed comprehensively. Three-dimensional laminar boundary layer computations were compared with data on the effect of angle of attack on conical transition, and a rather simple scaling law was derived. A technique was developed for simulating hypervelocity particle impact with a high power pulsed laser. The scaling requirements were derived, and a test program was conducted with a one joule ruby laser on a variety of surface materials. The validity of the simulation was demonstrated and many mass loss measurements were obtained. The behavior of ice crystals in shock layers was modeled using a two- layer melt removal analysis, a new dynamic fracture criterion for particle shattering, and an improved model for the deformation of the ice fragment cloud.