Aeroheating Measurements of BOLT Aerodynamic Fairings and Transition Module

The Air Force Office of Scientific Research (AFOSR) has sponsored the Boundary Layer Transition (BOLT) Experiments to investigate hypersonic boundary layer transition on a low-curvature, concave surface with swept leading edges. This paper presents aeroheating measurements on a subscale model of the BOLT Flight Geometry, aerodynamic fairings, and Transition Module (TSM) in the NASA Langley 20-Inch Mach 6 Air Tunnel. The purpose of the test was to investigate and identify any areas of localized heating on the TSM for inclusion in the BOLT Critical Design Review (CDR). Surface heating distributions were measured using global phosphor thermography, and data were obtained for a range of model attitudes and free stream Reynolds numbers. Measurements showed low heating on the fairings and TSM. Additional analysis was completed after the CDR to compare heating on the TSM for the nominal BOLT vehicle reentry angle-of-attack with heating on the TSM for possible reentry angle-of-attack excursions. The results of this analysis were used in conjunction with thermal analyses from Johns Hopkins Applied Physics Lab (JHU/APL) and the Air Force Research Laboratory (AFRL) to assess the need for thermal protection on the flight vehicle TSM

Implementation And Assessment Of An Algebraic Energy Flux Model For High Speed Gaseous Shear Flows

In current high speed Reynolds-averaged Navier-Stokes (RANS) simulations, the turbulent heat flux is often calculated directly from the modeled eddy viscosity, be it from 0-, 1-, or 2-equation models. An Algebraic Energy Flux (AEF) model, based on a truncation of the energy flux transport equation, provides an alternative with the potential for predicting all three components of the turbulent heat flux and accounting for non-equilibrium (e.g., mechanical) effects in shear layers. The objectives of the present study are to formalize the AEF model\u27s derivation and implementation into standard CFD codes and to provide further assessment with new high Mach number direct numerical simulation (DNS) data. The latter efforts demonstrated that the AEF approach consistently outperforms the traditional RANS technique over a range of pressure gradients, including for the first time favorable pressure gradients. However, there is space to improve the performance in the adverse pressure gradient and in the near wall region. The detail provided for each step of the derivation, especially in regard to the assumptions taken, provides a strong foundation for such future endeavors