Reduced-Order Aerothermoelastic Framework for Hypersonic Vehicle Control Simulation

Abstract

Hypersonic vehicle control system design and simulation requires models that contain a low number of states. Modeling of hypersonic vehicles is complicated due to complex interactions between aerodynamic heating, heat transfer, structural dynamics, and aerodynamics in the hypersonic regime. Though there exist techniques for analyzing the effects of each of the various disciplines, these methods often require solution of large systems of equations which is infeasible within a control design and evaluation environment. This work therefore presents an aerothermoelastic framework with reduced-order aerothermal, heat transfer, and structural dynamic models for time-domain simulation of hypersonic vehicles. The problem is outlined and aerothermoelastic coupling mechanisms are described. Details of the reduced-order models are given and a representative hypersonic vehicle control surface to be used for the study is described. The error between the reduced-order models is characterized by comparison with high-fidelity models. The effect of aerothermoelasticity on total lift and drag is studied and is found to result in up to 8% change in lift and 21% change in drag with respect to a rigid control surface for the four trajectories considered. An iterative routine is used to determine the necessary angle of attack needed to match the lift of the deformed control surface to that of a rigid one at successive time instants. Application of the routine to different cruise trajectories shows a maximum departure from the initial angle of attack of 7%.

Modeling and Analysis of Shock Impingements on Thermo-Mechanically Compliant Surface Panels

“…The shock generator height, h w , is prescribed to vary sinusoidally in time about a mean height, h w0 , at a frequency of 10 Hz, as defined by Eq. (40). Note that this yields a change of the shock generator's angle into the flow of about ±3 • about a 10 • nominal shape.…”

“…Typical approaches for model reduction of unsteady, nonlinear flows include proper orthogonal decomposition (POD), [36][37][38] Volterra series, 38,39 and surrogates. [40][41][42][43][44][45] Each of these seek to identify the primary features of a system from a limited number of high-fidelity flow solutions. The generation of this dataset requires an initial computational investment.…”

“…[13] was coupled with a CFD surrogate model for the pressure and heat flux. Finally, Falkiewicz et al 15 performed a partitioned dynamic aerothermoelastic analysis of a hypersonic control surface using several reduced order models. Model reduction for the thermal problem was achieved through a proper orthogonal decomposition basis and for the structural problem with a combination of Ritz and free vibration modes to account for geometric stiffening and material degradation.…”

“…There are a number of relevant previous studies to this problem, such as: high fidelity modeling of STBLIs; 3-8 partitioned fluid-thermal-structural analysis; [9][10][11][12][13][14][15][16] and shock impingements on compliant surfaces. [17][18][19] Each of these areas are briefly reviewed next.…”

“…For the fluid, the pressure was modeled with piston theory, and the heat load was modeled using a CFD surrogate. An important aspect of the recent literature [13][14][15][16] is the implementation of different time step sizes for the thermal and structural solvers; with boundary conditions passed from the structural solver to the thermal solver in a time-averaged sense. Originally proposed by Culler and McNamara,13 this was motivated by the large differences in characteristic time scales between the two domains.…”