Study of an air-breathing engine for hypersonic flight

A computationally efficient, quasi-one-dimensional, supersonic combustion model has been developed to simulate high-speed engine flowfields such as in a scramjet. The model can be used in design and optimization studies, where a wide range of engine inlet conditions may be encountered. The model solves a series of ordinary differential equations that come from the equations of fluid motion coupled with combustion. The effects of area change, wall skin friction, mass injection, fuel mixing, and heat transfer are included. The equations are derived assuming an open thermodynamic system with equilibrium or with finite-rate chemistry. Results will show the differences on combustor performance between considering equilibrium or not. The inclusion of chemical kinetics allows for a prediction of fuel ignition, a finite rate process that inherently cannot be predicted using equilibrium methods. Therefore, incorporating the timescales of fuel mixing and ignition is crucial for an accurate prediction of combustor performance in most scramjet operating conditions. Furthermore, the effects of dissociation, fuel mixing and friction are discussed. Eventually, a simple analysis of the air inlet and the nozzle is developed in order to have an overall vision of the scramjet and its feasibility