Aerothermoelastic Simulation of Air-Breathing Hypersonic Vehicles

Abstract

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. I. IntroductionYPERSONIC flight presents highly coupled physical processes that must be adequately modeled in order to design the vehicle and its flight control laws. Unsteady aerodynamics, structural dynamics, aerothermal heating, thermal degradation of material properties, geometric stiffening due to thermal gradients, and thermochemical processes all play integral roles in the performance of a hypersonic vehicle (HSV). Due to these coupled and generally complex processes, the reduction of HSV states to manageable numbers has been a daunting task and posed as a significant hurdle to the timely evaluation of vehicle response and stability.Past research by Bolender and Doman 1 described a two-dimensional longitudinal flight dynamics model which employed a combination of oblique shock, Prandtl-Meyer expansion, and a quasi-one-dimensional duct with heat addition to determine the stability characteristics of a two-dimensional HSV. The inclusion of shock-expansion theory, rather than the previously studied 2 Newtonian impact theory, allowed for the consideration of engine inlet spillage and inlet shock patterns which are both considered with respect to a movable inlet door intended to maintain a shock-on-lip condition. Pressures on the aft body resulting from the propulsion exhaust are also considered. Flat plates are used to approximate control surf...

Aerothermoelastic Analysis of a Hypersonic Vehicle Based on Thermal Modal Reconstruction

“…Parameter space and bounds Sampling points: x (1) , (2) ,⋯,x (Ns) Aerodynamic heating over rigid body using the CFD solver the CFD solver are computed. Secondly, a steady-state heat transfer analysis is performed using MSC Nastran (Sol 153).…”

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