Experimental Study On The Characteristics Of Continuous Rotating Detonation Of Hydrogen-rich Ga

A new engine composed of air turbo rocket and continuous rotating detonation engine has wide flight envelope and good thrust performance.The research on the continuous rotating detonation of fuel-rich gas and air is a necessary way to break through the key technology of new combined engine.Hydrogen-rich gas has high activity and low initiation difficulty.It is an ideal choice to explore the combustion fuel-rich gas and the propagation mechanism of rotating detonation wave.Therefore,in this paper,the continuous rotating detonation experimental research is carried out with hydrogen-rich gas as fuel and air as oxidant.The main research contents and conclusions are as follows:The experimental research on the stability of hydrogen/air rotating detonation was carried out.The working range of the engine is determined,and the factors affecting the stability of continuous rotating detonation are analyzed.It is found that when the equivalence ratio is less than 0.5,the engine is difficult to ignite and detonate,while when the air mass flow is 260 g/s,it is difficult for the engine to form stable continuous rotating detonation wave.When the air mass flow is greater than 360 g/s,the detonation wave can propagate stably and sustainably in the range of equivalence ratio 0.99～1.22.The stable working range of engine corresponding to different sizes of air injection circumferential seam is also different.The experimental research of continuous rotating detonation of hydrogen-rich gas was carried out,and the propagation characteristics of rotating detonation wave under different propagation modes was analyzed.In the experiment,when the equivalence ratio is greater than 1.06,the continuous rotating detonation wave presents single wave propagation mode.When the equivalence ratio is in the range of 0.87 ～ 1.06,it is the transition stage from single wave propagation mode to two-wave collision propagation mode.When the equivalence ratio is lower than 0.68,it is completely in the two-wave collision propagation mode.In addition,the propagation velocity increases with the increase of equivalence ratio,but the velocity does not increase significantly when it reaches the critical value.Due to the existence of two-wave collision mode,the deficit of average propagation velocity under transition mode and two-wave collision mode is large.The increase of air mass flow also helps to improve the propagation velocity of continuous rotating detonation wave.The experimental research on the self-initiation phenomenon of hydrogen-rich gas and air is carried out,and the influence of the interference of pre-detonation tube on the self-initiation propagation characteristics is analyzed.With the help of high-speed photography technology,the formation process of self-initiation of continuous rotating detonation is explained,and the influencing factors of self-initiation delay time and propagation characteristics are analyzed.At higher equivalence ratio and higher hydrogen-rich gas temperature,the self-initiation difficulty is low and the self-initiation delay time is short.When the air mass flow is large,the self-initiation delay time is generally long.The propagation characteristics of the continuous rotating detonation wave formed by self-initiation are consistent with the law obtained through the ignition of the pre-detonation tube.Increasing the pre-combustion oxygen mass flow increases the temperature of the hydrogen-rich gas,intensifies the early combustion of the hydrogen-rich gas and air,and reduces the pressure and propagation speed of rotating detonation wave to some extent.