Study on fuel/air mixing based on oblique detonation engine

Abstract Currently, the inflow conditions used in the study of oblique detonation engines are ideal premixed inflow, and there are few studies on non-premixed inflow. The fuel mixing process in the flow field structure and mixing degree for forming oblique blast waves has essential significance. This paper uses a combination of theoretical analysis and numerical simulation to study the inlet section of the oblique detonation engine. The governing equations are the inviscid Euler equations coupled with chemical reaction source terms, and the second-order TVD scheme is used to solve the equations. First, this paper compared the influence of the single hydrogen nozzle parameters on the flow field structure and the hydrogen mole fraction distribution at the outlet, optimized the hydrogen jet structure, and analyzed the coupling effect between the incoming flow and the jet. The closer the nozzle location is to the supersonic inlet, the lower the Mach number, and the higher the equivalence ratio of hydrogen to oxygen, the better the fuel and air mixing effect. And too large or too small hydrogen injection angle will make the hydrogen too concentrated on the wall and insufficient penetration depth, which reduces the mixing of hydrogen. Secondly, while maintaining the same fuel mass flow rate as the single hydrogen nozzle, this paper increases the number of hydrogen nozzles, thereby increasing the obstruction to the incoming flow and improving the fuel mixing effect. Finally, because the physical ramp and aerodynamic ramp as a method of increasing mixing will lead to fuel concentration on the wall, which is not conducive to the subsequent combustion, this paper proposes an optimization model of the strut injection method. The results show that strut injection can effectively improve the mixing degree of hydrogen and air at the exit and solve the problem of fuel concentration at the wall by using the staggered jet and baroclinic effect of hydrogen. This paper reveals the law of fuel injection in the inlet and provides essential data support for studying oblique detonation engines in a non-premixed environment.