Aeroheating Design Issues for Reusable Launch Vehicles -- A Perspective

Abstract

An overview of basic aeroheating design issues for Reusable Launch Vehicles (RLV), which addresses the application of hypersonic ground-based testing, and computational fluid dynamic (CFD) and engineering codes, is presented. Challenges inherent to the prediction of aeroheating environments required for the successful design of the RLV Thermal Protection System (TPS) are discussed in conjunction with the importance of employing appropriate experimental/computational tools. The impact of the information garnered by using these tools in the resulting analyses, ultimately enhancing the RLV TPS design is illustrated. A wide range of topics is presented in this overview; e.g. the impact of flow physics issues such as boundary-layer transition, including effects of distributed and discrete roughness, shockshock interactions, and flow separation/reattachment. Also, the benefit of integrating experimental and computational studies to gain an improved understanding of flow phenomena is illustrated. From computational studies, the effect of low-density conditions and of uncertainties in material surface properties on the computed heating rates are highlighted as well as the significant role of CFD in improving the Outer Mold Line (OML) definition to reduce aeroheating while maintaining aerodynamic performance. Appropriate selection of the TPS design trajectories and trajectory shaping to mitigate aeroheating levels and loads are discussed. Lastly, an illustration of an aeroheating design process is presented whereby data from hypersonic wind-tunnel tests are integrated with predictions from CFD codes and engineering methods to provide heating environments along an entry trajectory as required for TPS design. I.

Physical criterion study on forward stagnation point heat flux CFD computations at hypersonic speeds

“…However, there is no convincing principle about how to choose them. Zoby et al [5] reviewed existing thermal environment prediction methods and believed that in current circumstances, people should continue to develop high-precision numerical schemes for a high resolution of the flow field, and another way of great importance was to unveil the specific physical characteristics of hypersonic flows. This inspires us that a careful theoretical analysis should be exploited to find the physical criteria for judging the reliability of the stagnation point heat flux computations.…”

Simulation of Second-Mode Instability in a Real-Gas Hypersonic Flow with Graphite Ablation

“…Practical methods for ablation prediction employ various levels of simplification, ranging from empirical engineering correlation and approximate semiempirical integral methods to very detailed full Navier-Stokes simulation methods that model the nonequilibrium, chemically reacting, fluid dynamics coupled to in-depth heat conduction material models [4][5][6][7][8][9]. Surface chemistry models are commonly used in full Navier-Stokes simulations to more accurately model surface species concentrations and mass blowing rates.…”

High-Order Shock-Fitting Method for Hypersonic Flow with Graphite Ablation and Boundary Layer Stability

“…[2][3][4][5][6][7] Surface chemistry models are commonly used in full Navier-Stokes simulations to more accurately model surface species concentrations and mass blowing rates. Some common surface chemistry models are that of Zhluktov and Abe 8 and Park.…”