Control-oriented 3D Modeling of Flexible Hypersonic Vehicles

Abstract

Hypersonic vehicles may eventually allow dramatic reductions in flight times for both commercial and military applications. Direct access to Earth orbit without the use of separate boosting stages may also become possible as scramjet-powered aircraft enter service. Maintaining controlled flight is among the greatest challenges facing the development of hypersonic vehicles. Complex interactions among the airframe, propulsion system, and vehicle aerodynamics prevent each vehicle sub-system from being developed independently. Because of this, computational flight simulations are a vital tool in the development of hypersonic vehicles. Dynamic models of these vehicles tend to be highly complex and multi-disciplinary due to strong interaction between aerodynamics, propulsion, structure, and controls. The goal of control-oriented models of hypersonic vehicle is developing reduced-order models with “sufficient fidelity” to capture missioncritical control-centric phenomena. Component Mode Synthesis compared with FEA can substantially decreases the number of system equations with a little decreased in accuracy. Component Mode Synthesis is the better method to get the enough accurate of the structure and use less time. Firstly the hypersonic vehicle was divided into three parts of body, left wing and right wing. The Component Mode Synthesis method presented in this paper was to calculate flexible modes of the branch beams for the determination of the flexible modes of an air-breathing hypersonic vehicle. Then the coupled dynamic model was developed, the steady/unsteady aerodynamic model of the 3D hypersonic elastic vehicles was calculated using steady shock-expansion theory with an unsteady correction from piston theory, and one-dimensional scramjet engine model was used to determine the thrust force. Finally, the coupled dynamic model was trimmed and linearized. Numerical results of a rigid model， one-dimensional beam flexible model and the branch beams flexible model were given, at last the dynamic properties of different cases ware discussed.