Modelling for couplings of an airframe—propulsion integrated hypersonic vehicle with engine safety boundaries

Abstract A model for coupled dynamics of an airframe—propulsion integrated hypersonic air-breathing flight vehicle with various engine safety boundaries, called HIT-HAV (Harbin Institute of Technology), was developed to analyse the couplings among flight dynamics, aerodyna-mics, propulsion, and control. These engine safety boundaries included inlet unstart boundary, burner wall temperature limitation, burner lean fuel combustion boundary, rich fuel combustion boundary, and so on. All these engine safety boundaries were considered in modelling the HIT-HAV. The validity and practicability of the model were verified by comparing with a full-scale generic hypersonic vehicle. By simulating the HIT-HAV model, the conclusion was drawn that due to the couplings among flight dynamics, aerodynamics, propulsion, and control, the airframe—propulsion integrated hypersonic air-breathing flight vehicle may operate, beside the normal operation mode, near some safety boundaries and may even exceed them, which may cause a failure flight. A hypersonic air-breathing flight vehicle's un-safety operation mode could be avoided by limiting the fuel supply, which has been verified in simulations. This paper indicates that for an airframe—propulsion integrated hypersonic air-breathing flight vehicle with various engine safety boundaries, as there were various relevant operation modes requested by various engine safety boundaries, an independent flight control and propulsion control in the traditional sense would fail to satisfy the hypersonic air-breathing flight and hence a multi-mode control design should be the focus of future research.