AIAA 99-3559 X-33 Computational Aeroheating Predictions and Comparisons

The goal of the NASA Reusable Launch Vehicle (RLV) technology program is to develop and demonstrate essential, cost-effective technologies for next-generation launch systems. The XÐ33 flight vehicle presently being developed by Lockheed-Martin is an experimental Single-Stage-to-Orbit (SSTO) demonstrator that is intended to validate critical technologies for the full-scale RLV. One of the key technologies to be demonstrated on the XÐ33 vehicle is an advanced, metallic thermal protection system (TPS). As part of the development of this TPS system, the aeroheating environment of the X-33 is being defined through conceptual analysis, ground-based wind-tunnel testing and computational fluid dynamics (CFD). This report provides an overview of the hypersonic aeroheating CFD research conducted at the NASA Langley Research Center (LaRC) in support of this TPS development activity. In this research, laminar and turbulent aeroheating predictions were generated at wind-tunnel test conditions for the XÐ33 vehicle using both a finite-volume, Navier-Stokes solver, and a coupled inviscid-solver/boundary-layer-code engineering method. Computations were performed for angles-of-attack of 20û, 30û, and 40û. Comparisons between the predictions and wind tunnel data for the centerline and axial heating distributions were generally within ±10% for the Navier-Stokes method and ±25% for the engineering code method. Aeroheating distributions were also computed for the peak heating point on the flight trajectory. Nomenclature H enthalpy (J/kg) h heat transfer coefficient (kg/m 2-sec), h = q ú / (H aw-H w) h FR Fay-Riddell heating coefficient (kg/m 2-sec) L reference length (m) M Mach number p pressure (N/m 2) q ú heat transfer rate (W/m 2) Re Reynolds number T temperature (K) U ¥ freestream velocity (m/sec) X,Y,Z coordinate system (m) a angle-of-attack (deg) r density (kg/m 3) Introduction The Access to Space Study 1 conducted by NASA recommended the development of a fully Reusable Launch Vehicle (RLV) 2,3,4 to provide a next-generation launch capability at greatly reduced cost. This recommendation led to the RLV/XÐ33 technology program, an industry-led effort in partnership with NASA. As part of this program, the XÐ33 is intended to serve as a sub-scale technology demonstrator for a full-scale Single-Stage-to-Orbit (SSTO) RLV. The XÐ33 is intended to prove the feasibility of the SSTO-RLV concept through demonstration of key design and operational aspects of the vehicle. Following a Phase I industry competition between several aerospace companies, the Lockheed-Martin lifting-body concept was selected by NASA for award of the Phase II contract to design, develop and construct an XÐ33 flight vehicle. The Lockheed-Martin …