An Aero-Propulsion Integrated Elastic Model of a Generic Airbreathing Hypersonic Vehicle

A combined analytic and CFD-based two-dimensional airbreathing generic hypersonic flight vehicle model has been developed for control design and flight simulation environment. The vehicle, CSULA-GHV, is inspired by a set of mission requirements broadly accepted for a hypersonic cruise vehicle intended as a reusable launch vehicle (RLV) for access to space or for military application. The GHV has a simple configuration consisting of a fore-body diffuser, a scramjet engine, and an aft-body expansion nozzle. Longitudinal control is affected by the thrust setting (hydrogen fuel rate) elevon deflection. Complete aerodynamic, coupled aero-propulsion and aeroelastic data for the vehicle are presented in graphic format, and polynomial form using FLUENT CFD simulations at various Mach numbers, angles of attack, fuel rate and elevon settings. The interaction between aerodynamics, propulsion system, and vehicle elasticity are calculated and quantified. For control design, a set of nonlinear longitudinal equations of motion for the vehicle are presented which include both an inverse square law, gravitational model and the centripetal acceleration. The combined analytic-CFD approach is used to generate the static aerodynamic and propulsion data in the form of polynomial expressions. The vehicle's structural dynamics are accounted for by assuming that elastic deformations in the first few modes amount to an effective change in angle of attack and elevon effectiveness. These changes in turn affect engine performance and control surface effectiveness. Structural modes are obtained from a finite element model using NASTRAN.