Numerical Study Of Enhancing Detonation Stability In Supersonic Flow

Detonation combustion has many advantages,such as high efficiency of ther modynamic cycle,self pressurization and fast heat release,so it has a broad application prospect in hypersonic propulsion field.Scramjet based detonation combustion can achieve partial or complete detonation combustion in its combustion chamber,thus improving the thrust performance of the engine.However,it is relatively difficult to achieve detonation initiation and dynamic stable propagation in supersonic flow.In this paper,numerical simulation and theoretical analysis of adaptive mesh refinement are used to investigate the detonation initiation and propagation stability enhancement in supersonic flow.Taking into account the influence of continuous hot jet on the reliable detonation and propagation stability in complex configuration,Numerical simulation of detonation initiation and propagation induced by hot jet in a complex combustion chamber with expanded wall and cavity was carried out.The results show that the expansion effect of the expanded wall plays an important role in accelerating the formation of the three wave point of the detonation wave,suppressing the propagation of detonation wave and increasing the instability of the wave front.The pressure oscillation in the cavity has the effect of enhancing the detonation wave intensity,but the effect of the cavity is limited under the action of the hot jet.Stability enhancement of detonation wave propagation under the combined action of cavity and expansion wall can achieve.The influence of the expanded angle,the width and the depth of the cavity on the detonation initiation and propagation in the supersonic flow was obtained.In order to deeply analyze the influence of cavity and expanded wall on the propagation stability of detonation wave,numerical simulation of detonation wave propa gation after hot jet was closed was carried out.The results show that the existence of the expanded wall causes the formation of the underdriven detonation more easily,and the detonation wave attenuates gradually,and the detonation bifurcation structure formed on the expanded wall further accelerates detonation failure.The existence of the cavity enables the oblique shock wave to be stationed at the front of cavity,and the double-wave structure consisting of the stationary shock and the shock wave at expanded wall plays a key role in the re-initiation of the detonation.The long duration self-sustaining propagation of detonation waves in the combustion chamber can be achieved by the combination of the cavity and the expanded wall.The influence of dy-namic pressure on detonation wave propagation is obtained.To explore a way to realize the dynamic stability of detonation wave,a numerical study on the detonation initiantion and propagation in a straight tube with porous suction wall is carried out.The results show that the accelerated expansion of the product caused by suction plays an important role in weakening the transverse wave,changing the curvature of the detonation wave surface and suppressing the propagation of detonation wave.It is the balance achieved between the inhibitory action of suction and the echancenment of hot jet that realize the dynamic stabilization of the detonation wave in the supersonic flow.By controlling the intensity of the hot jet or changing the number of the suction holes,the position of the dynamic stable of the detonation wave can be changed.