A quasi-one-dimensional analytical study on the propulsive performance of an oblique detonation engine utilizing different inlets

Oblique detonation engines (ODEs) utilize standing oblique detonation waves (ODWs) to organize combustion, making them particularly well-suited for hypersonic air-breathing propulsion systems. Previous researches have predominantly concentrated on the flow physics of ODWs, with most experimental and computational studies employing a two-dimensional inlet or omitting the inlet’s compression process. Advanced inlet designs play a crucial role in enhancing the propulsive performance of air-breathing vehicles. This paper presents a comparative analysis of the specific impulse between an ODE vehicle equipped with a three-dimensional inward-turning inlet and one with a two-dimensional inlet at various design points, utilizing a quasi-one-dimensional performance analysis model specifically developed for ODE vehicles. Due to the superior total pressure recovery of the three-dimensional inward-turning inlet, the vehicle equipped with this inlet demonstrates enhanced thrust performance compared to its counterpart with a two-dimensional inlet, except under conditions of lower equivalence ratios (≤ 0.6). This paper systematically investigates the influence of flight altitude, flight Mach number, fuel injection parameters, combustor wedge angle, nozzle expansion area ratio, and nozzle flow model (chemical equilibrium flow and frozen chemistry flow) on the specific impulse of the vehicle, utilizing a quasi-one-dimensional performance analysis model. Among these factors, the flight Mach number, wedge angle, nozzle expansion area ratio, and nozzle flow model have a significant impact on the vehicle’s specific impulse. Additionally, the equivalence ratio and the total temperature of the fuel injection also play an important role in determining the specific impulse. To facilitate the engineering application of the ODE, it is essential to incorporate the three-dimensional inward-turning inlet into the ODE vehicle’s design.