Songbai Yao

Analytical and Numerical Investigations of Wedge-Induced Oblique Detonation Waves at Low Inflow Mach Number

The wedge-induced oblique detonation wave (ODW) at low inflow Mach number is investigated via Rankine–Hugoniot analysis and numerical simulations. The results show that the Chapman–Jouguet oblique detonation wave (CJ ODW) plays a significant role in the structure of the ODW. And the influence of the CJ ODW is the reason why an attached ODW can propagate upstream. Both the analytical and numerical results show that the decrease of inflow Mach number and the increase of wedge angle are conducive to the upstream propagation of ODW. In the upstream propagation process, a Mach reflection wave configuration is always established on the wedge surface. For the upstream propagating ODW that cannot detach from the wedge surface by itself, it will stabilize at a point on the wedge surface with an induction region, which is a few times the length of the induction zone of an ideal Zeldovich–von Neumann–Döring (ZND) detonation. Benefiting from the short induction region, the stabilized upstream propagating ODW has extraordinary stability.

Numerical Investigation of Spontaneous Formation of Multiple Detonation Wave Fronts in Rotating Detonation Engine

This article presents a three-dimensional (3D) numerical study on rotating detonation engine (RDE), using the premixed stoichiometric hydrogen-air mixture. Different from a conventional numerical setting, intervals are set in the gas intake configuration to bring in effects of nonuniform injection in numerical simulation, which is more semblable to the actual condition in experiments. The simulation successfully shows the spontaneous formation of multiple detonation wave fronts. Discussion is carried out about the factors that affect the phenomenon of multiple detonation wave fronts, which may be helpful to enhance the stability and repeatability of the detonation initiation in RDE experiments. Then subsequently, the simulation result of a typical case is thoroughly described. Three stages of the spontaneous formation of multiple detonation wave fronts after initiation are analyzed. This typical case is also compared to both the conventional simulation and the experimental results to verify its effectiveness.

Three-Dimensional Numerical Study of Flow Particle Paths in Rotating Detonation Engine with a Hollow Combustor

ABSTRACT A three-dimensional simulation is performed to study rotating detonation engines (RDEs) with a hollow combustor. The simulation tracks some representative flow particles and makes an analysis of their evolution process in the rotating detonation flow, including their trajectories and the variation of their physical properties. The study shows that there are mainly two types of trajectories of these tracked particles. The particles in the outer region of the chamber present smooth paths and flow downstream quickly along the outer wall. The particles in the inner region, by contrast, show relatively winding paths before passing through the chamber. Overall, most of the flow particles are ejected almost along the axial direction. The physical properties of the flow particles change rapidly and evidently when they encounter the detonation front. The oblique shock wave induced by the detonation wave has a compression effect on the flow particles. This compression effect, however, is much smaller compared with that of the detonation front. The present study helps to explore some details of the detonation flow in the hollow combustor and shows that the hollow RDE has the advantage of generating a stable thrust.

Numerical Investigation of Effects of Fuel Injection on Rotating Detonation Engine

A series of three-diemensional simulations of rotating detonation engine (RDE) are carried out using a one-step chemistry model to investigate the effects of fuel injection. Four specific injection patterns are used and it shows that the propulsive performance of RDE is not distinctly affected by the fuel injection patterns, in the respect of fuel-based specific impulse. Besides, one of the injection patterns is found to induce multiple detonation waves in RDE. This specific injection pattern is then studied in detail to discuss this phenomenon.

Continuous Detonation Engine Researches at Peking University

In this chapter we reviewed the research of the continuous detonation engine (CDE) performed at Peking University. The research team at Peking University was the first to conduct numerical and experimental research of the CDE in China. We designed several types of CDE combustion chambers and carried out experiments to verify its feasibility. In addition, we have performed a series of two- and three-dimensional simulations of the CDE. Numerical studies covered many aspects of the CDE, including the detailed flow structure, fuel injection, nozzle design, viscous effect, propulsive performance, initiation method, particle path, thermodynamic performance, shock wave reflections near the head-wall, spontaneously formation of multiple detonation waves, etc. In this chapter, we also discussed several recent examples of progress and accomplishments.

Numerical Study of the Propulsive Performance of the Hollow Rotating Detonation Engine with a Laval Nozzle

Abstract The aim of the present paper is to investigate the propulsive performance of the hollow rotating detonation engine (RDE) with a Laval nozzle. Three-dimensional simulations are carried out with a one-step Arrhenius chemistry model. The Laval nozzle is found to improve the propulsive performance of hollow RDE in all respects. The thrust and fuel-based specific impulse are increased up to 12.60 kN and 7484.40 s, respectively, from 6.46 kN and 6720.48 s. Meanwhile, the total mass flow rate increases from 3.63 kg/s to 6.68 kg/s. Overall, the Laval nozzle significantly improves the propulsive performance of the hollow RDE and makes it a promising model among detonation engines.