Centerline heating methodology for use in preliminary design studies

Abstract

The initial design of aerospace entry systems requires rapid but accurate predictions of vehicle performance across the fields of structures, aerodynamics, guidance and thermodynamics. A methodology for an increase in the fidelity of aerothermodynamic heating with a minimal impact on simulation time is presented. An investigation of the fidelity levels and associated complexity of different engineering relations has been conducted which demonstrates the usefulness and applicability of stagnation point and streamline heating methods. In order to increase the fidelity of stagnation point methods, a curve fit for the effective nose radius of arbitrary blunt bodies has been established. The effective nose radius formulation utilizes the Configuration Based Aerodynamic (CBAERO) program to model effective nose radius as a function of Mach number, dynamic pressure, and altitude for a wide range of geometries and angles of attack. In addition, a program has been developed to model the heating along the windward centerline. This program uses a mix of engineering-level relations for aerodynamic heating both on and off the stagnation point. The development of the boundary layer heating model along the vehicle centerline and the associated boundary layer edge conditions is shown. The program is able to calculate heating distributions on axisymmetric bodies and heating along the windward centerline for general geometries at angle of attack. The results have shown good validation to CBAERO and experimental results. Finally, an integrated vehicle and trajectory design space exploration is given for Prompt Global Strike missions which demonstrate the design improvement afforded by the centerline heating model with integrated thermal protection system sizing. This is shown through a Pareto frontier shift in a comparison of range versus payload volume metric, as well as key locations of thermal impact on maximum downrange and geometry configuration.

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