Longitudinal Dynamic Studies On Hypersonic Vehicle

As a new kind of near space aircraft, hypersonic vehicles, which have superior military andcivilian value, are becoming the focus and hotspots research in the internationally. Compared withconventional aircraft, hypersonic vehicles commonly use integrated design and the model is alwaysnon-linear, strong-coupled and uncertainty. The relevant studies are just in process. Based on acomprehensive review of hypersonic vehicle’s current development, this paper focuses on thesevehicles’ longitudinal dynamics and relevant problems.First, taking a typical longitudinal hypersonic vehicle model for the study, then a model based onintegrated design for aerodynamic-propulsion was constructed. The oblique-shock and Prandtl-Meyertheory was applied to compute the aerodynamic forces, which can figure out the flow propertiesbehind shocks and their positions more accurately. An air-breathing scramjet basic model was usedhere, then calculated and analyzed the propulsion-airframe coupling characteristics. Based on theexisting work, an in-depth discussion of the impact on thrust and aerodynamic due to engine’s designparameters was obtained, and got some meaningful conclusions.Using Lagrange equation and the principle of virtual work, we had performed an elasticdynamics model for a longitudinal hypersonic vehicle. Then we had done some related research anddiscussion on the coupled dynamics model, including trim and stability analysis. The results show thatthe model can reflect the strong coupled feature of hypersonic vehicles well.Then the non-linear dynamic model was linearized at one equilibrium point, the LQR theory wasapplied to design an instruction trace controller for the linearized model. A tracing test of velocity andattitude was simulated and analyzed in Simulink. The results present good performances of theinstruction tracing controller.