液体火箭发动机背压振荡环境下的雾化特性研究进展

Recent Advances of Atomization Characteristics under Oscillating Backpressure Conditions in Liquid Rocket Engines

关键词:  液体火箭发动机  背压振荡  雾化特性  燃烧不稳定  Klystron效应

Key words:  Liquid rocket engines  Backpressure oscillations  Atomization characteristics  Combustion instability  Klystron effect

摘要:

为加深对背压振荡环境下雾化特性的认识，针对在液体火箭发动机中广泛应用的气液同轴直流式喷嘴、撞击式喷嘴与离心式喷嘴，综述了背压振荡环境下单束液体射流、气液同轴射流、射流撞击以及旋流雾化特性的研究进展，总结了背压振荡影响雾场的主要作用机制，阐述了以往研究中存在的一些问题以及需要突破的若干关键技术难题。通过综述可知，背压振荡主要通过两个方面影响雾场：一是通过改变喷注压降影响喷射，继而影响雾化过程；二是通过振荡的气相流场直接作用于雾场。背压振荡环境下的雾化研究仍需要开展大量工作，且需要突破以下几个技术难点：在试验方面，需要设计可以产生高频率、高幅值压力振荡的反压舱装置，同时对雾场的干扰要降到最小；发展先进的光学诊断方法，可以用于反压舱内雾场信息的提取；在数值模拟方面，需要开展雾化过程的高精度数值模拟，同时研究压力波的产生、发展及演化过程，在这两点基础上研究背压振荡与雾场的相互作用。

Abstract:

In order to acquire a better understanding of atomization characteristics under oscillating backpressure conditions, as to gas liquid shear coaxial injector, impinging jet injector and swirl injector that are widely used in liquid rocket engines, the present study reviews recent advances of atomization characteristics of a single liquid jet, gas liquid shear jet, impinging jets, and swirling flow under oscillating backpressure conditions. The main action mechanism of backpressure oscillations on atomization is summarized. Also some problems that existed in previous studies and the key technology that needs breaking through are interpreted. By the review it is concluded that oscillating backpressure affects the atomization field mainly by two ways. One way is to change pressure drop to influence injection thus to affect the atomization process. The other way is to affect atomization directly by oscillating gas field. Plenty of work still needs to be done to study atomization characteristics under oscillating backpressure conditions while some technical difficulties below should be overcome. As for the experiments, backpressure capsule that can generate high-amplitude and high-frequency oscillating backpressure is demanded. At the same time, the disturbance to the atomization field should be at the least. Advanced optical diagnostic apparatus is demanded to acquire atomization field information in the backpressure capsule. As for the simulation, high-fidelity numerical simulation of atomization should be carried out. Also the generation, development, and propagation of pressure wave should be studied. The interaction between oscillating backpressure and atomization field should be investigated based on the two points mentioned above.