Aerothermoelastic Simulation of Air-Breathing Hypersonic Vehicles

This paper describes the development and implementation of a partitioned-based, multiphysics, multi-fidelity simulation framework for flexible hypersonic vehicles. This simulation framework will enable the study of the dominant physics needed for the generation of control-oriented models and will provide a reference model for flight control evaluation. A partitioned-based solution is employed to approach the problem of modeling a flexible hypersonic vehicle by dividing the vehicle into discrete regions within which unique combinations of physical processes are relevant. The dominant physics of each region are then modeled locally and information is exchanged across region interfaces at predetermined time intervals as the vehicle simulation is marched forward in time. The highly coupled physical processes within each region are modeled using an array of variable fidelity reduced order models. The partition solution implementation is compared to a monolithic solution through trim and time simulation of a sample hypersonic vehicle geometry. Trim results of rigid and flexible vehicle models show good matching between the partitioned and monolithic solutions for Mach 6, 26 km altitude, steady level flight. Time simulations at the same flight conditions also show good qualitative matching between the solutions, but a mismatch in effective mass distribution allows the monolithic vehicle model to have a slightly faster control response to a commanded elevon deflection. The partitioned solution code architecture is then extended to the characterization of flutter for a hypersonic lifting surface, showing a significant reduction of flutter Mach number as a function of flight time.