Performance modelling and numerical simulation validation of hypersonic inlet with fuel pre-injection

Abstract Fuel pre-injection in the inlet of a hypersonic engine has been proven to be advantageous in the range of the very high flight Mach numbers. In this paper, a rapid inlet performance analysis model with fuel pre-injection is proposed. The modelling process is divided into two stages. Firstly, the baseline inlet model is provided based on the working principle of the inlet. Then, the newly proposed fuel injection and heat release model is added to the baseline inlet model. Among them, the fuel injection and heat release model is equivalent to increasing the compression angle in the cold state. And in the hot state the effect of the fuel heat release will be considered in addition to the effect of cold state. The research results show as the equivalence ratio increases, the equivalent compression angle also increases, but the two are not in a linear relationship. Based on this pattern of effect, fuel injection can be used to regulate the shock wave position and accurately control the flow rate of the inlet. In addition, by comparing to numerical simulation, it is found that the analysis model can almost reasonably predict the performance of the pre-injection inlet. However, the calculation of drag coefficient has some deviation compared to numerical simulation, which is probably due to the lack of consideration of friction drag and the interaction between the shock wave and boundary layer in the model analysis. Overall, the modelling method proposed in this paper can reflect the effect of fuel injection on inlet performance, which can be used to optimise injection strategy in the future.