Research On Atomization Characteristics Of Liquid Pulsed Jet In Supersonic Crossflow

The atomization of pulsed injection liquid in supersonic gas crossflow are studied through the experiment and simulation in this paper,and the dynamic process of atomization is focused on,which establishes the theoretical basis for the application of this jet method.The flow field structure of the steady jet is studied as the basis for studying the pulsed jet.The time-average flow field of the gas phase was obtained by the RANS numerical simulation method.The gas-liquid interface was tracked by the mesh adapted technique.The jet trajectory calculated was in good agreement with the experiment.The effects of momentum flux ratio and orifice shape on the flow structure such as bow shock angle,position of the boundary layer separated and shock standoff distance are analyzed.The dynamic process of the square pulsed jet controlled by a solenoid valve in the supersonic crossflow is studied.In experiment of single pulsed jet,it was found that the unsteadiness of the jet of jet liquid had little effect on the depth of jet penetration.In the jet experiment of continuous pulse injection,it is found that the jet penetration depth at a certain flow rate can be adjusted by the duty circle,thereby realizing active control of the atomization and combustion process.As the decreases with the duty cycle of pulsed jet,the jet velocity increases,the secondary breakup become faster,and the drop size in the same downstream position is smaller by 29.4%.The atomization of the pulse jet with sinusoidal oscillation of liquid jet velocity are studied.The sinusoidal excitation of the flow oscillating is simulated by the flow oscillator.The morphology of liquid jet under the low-frequency combustion instability condition of the scramjet is simulated.Because the instability frequency of the combustion is far from the unstable frequency of the jet itself,the Klystron effect has a weak influence on the spray pattern.In the simulation study,the effect of the Klystron effect on the atomization process was studied using a fine supersonic two-phase large eddy simulation solver,and the oscillating jet was used as an injection method to improve the atomization characteristics.The simulation results show that when the frequency of the velocity pulsation reaches the Rayleigh-Taylor instability frequency of the jet itself,it will replace the Rayleigh-Taylor instability dominant the jet primary breakup,and find that the velocity pulsation of the jet effectively improves the mixing effect of liquid jet with the crossflow,the width of wake zone can be expended by 25%,the penetration can be increased by 20%.