Experimental observations together with theoretical analysis were conducted to investigate the break phenomenon and the corresponding mechanisms of self-pulsation for a liquid-centered swirl coaxial injector with rece...Experimental observations together with theoretical analysis were conducted to investigate the break phenomenon and the corresponding mechanisms of self-pulsation for a liquid-centered swirl coaxial injector with recess number of RN=1.Instantaneous spray images were obtained based on background light imaging technology with a high-speed camera.By dynamic analysis of the flow process of the liquid sheet in the recess chamber,a 1D self-pulsation theoretical model was established,and the self-sustaining mechanisms of self-pulsation were analyzed in depth.The results show that the increase of the momentum flux ratio will lead to the occurrence of the break phenomenon of self-pulsation for the injector with a larger recess length,and the frequency and intensity of self-pulsation before and after the break phenomenon differ significantly.The flow dynamics in the recess chamber sequentially transform from a periodic expansion-dominated flow to a stable flow,and then develop to a periodic contraction-dominated flow during the break process of self-pulsation.With the occurrence of self-pulsation before the break phenomenon,the liquid sheet has little effect on the pressure disturbance in the recess chamber.In contrast,with the occurrence of self-pulsation after the break phenomenon,the pressure disturbance is obviously affected by the liquid sheet.Based on the theoretical analysis model of self-pulsation,the self-pulsation frequency can be predicted.Furthermore,the self-sustaining mechanism of self-pulsation before and after the break phenomenon is preliminarily confirmed.The energy transfer between the gas-and liquid-phase is an important factor for maintaining the self-pulsation process.展开更多
During the experiment of gas/liquid coaxial swirl injector conducted with air and water under atmosphere environment, it is observed that the injector may selfoscillate. The self oscillation periodically occurs and va...During the experiment of gas/liquid coaxial swirl injector conducted with air and water under atmosphere environment, it is observed that the injector may selfoscillate. The self oscillation periodically occurs and vanishes with the increasing velocity of the gas flow.A theoretical model is presented based on the experiment investigation. Simulation of the acoustic process has been performed and conclusions consistent with the experiment can be drawn from the theoretical model, which explains the exPeriment phenomena quite well. At last, the comparison between phenomena of the self oscillation and some experiments of LRE indicates that some instability phenomena in oxygen/hydrogen propellant rocket engine may be the related to self oscillation in coaxial injectors展开更多
基金supported by the National Natural Science Foundation of China(No.11872375)the National Science Foundation for Young Scientists of China(Nos.11802323,11902351,and 12102462)。
文摘Experimental observations together with theoretical analysis were conducted to investigate the break phenomenon and the corresponding mechanisms of self-pulsation for a liquid-centered swirl coaxial injector with recess number of RN=1.Instantaneous spray images were obtained based on background light imaging technology with a high-speed camera.By dynamic analysis of the flow process of the liquid sheet in the recess chamber,a 1D self-pulsation theoretical model was established,and the self-sustaining mechanisms of self-pulsation were analyzed in depth.The results show that the increase of the momentum flux ratio will lead to the occurrence of the break phenomenon of self-pulsation for the injector with a larger recess length,and the frequency and intensity of self-pulsation before and after the break phenomenon differ significantly.The flow dynamics in the recess chamber sequentially transform from a periodic expansion-dominated flow to a stable flow,and then develop to a periodic contraction-dominated flow during the break process of self-pulsation.With the occurrence of self-pulsation before the break phenomenon,the liquid sheet has little effect on the pressure disturbance in the recess chamber.In contrast,with the occurrence of self-pulsation after the break phenomenon,the pressure disturbance is obviously affected by the liquid sheet.Based on the theoretical analysis model of self-pulsation,the self-pulsation frequency can be predicted.Furthermore,the self-sustaining mechanism of self-pulsation before and after the break phenomenon is preliminarily confirmed.The energy transfer between the gas-and liquid-phase is an important factor for maintaining the self-pulsation process.
文摘During the experiment of gas/liquid coaxial swirl injector conducted with air and water under atmosphere environment, it is observed that the injector may selfoscillate. The self oscillation periodically occurs and vanishes with the increasing velocity of the gas flow.A theoretical model is presented based on the experiment investigation. Simulation of the acoustic process has been performed and conclusions consistent with the experiment can be drawn from the theoretical model, which explains the exPeriment phenomena quite well. At last, the comparison between phenomena of the self oscillation and some experiments of LRE indicates that some instability phenomena in oxygen/hydrogen propellant rocket engine may be the related to self oscillation in coaxial injectors
