喷前压力脉动对撞击式喷嘴雾化特性的影响

Effects of Pressure Pulsation Upstream of Injector on Impinging Injector Atomization

关键词:  撞击式喷嘴  压力脉动  雾化  响应特性

Key words:  Impinging injector  Pressure pulsation  Atomization  Dynamic response

摘要:

为研究液体火箭发动机供应系统压力脉动对撞击式喷嘴雾化特性的影响，进行了撞击式喷嘴的动态雾化实验。通过脉动装置在喷嘴供应系统上施加不同频率和幅值的周期性压力脉动，利用两套高速摄影系统分别获得了动态雾化图像和雾场横截面上的散射光强，以此分析了撞击式喷嘴对喷前周期性压力脉动的响应频率和响应幅值范围及其对平均雾化角度的影响。结果表明，在研究的脉动频率范围内(0～4050Hz)，当喷前压力脉动幅值大于某一阈值后，雾化出现了明显的周期性质量聚集现象，其频率与喷前压力脉动的频率相同。脉动幅值增加，散射光强度的振荡幅值也增加，参与混合燃烧过程的介质流量振荡幅值加剧。平均雾化角度受脉动频率和幅值的影响都较小，变化范围处在均值的±4%以内。

Abstract:

In order to investigate the effects of pressure pulsation of feed system on the atomization characteristic of an impinging injector in liquid rocket engines，the cold flow experiments on the dynamic response of liquid jet atomization have been carried out with water as the working fluid. Controlled perturbations of the injector inlet mass flow were realized by using a hydromechanical pulsator. Images of spray and scattered light intensity of a cross-section of spray field obtained using two high-speed photography systems were used to assess the range of the response frequency and amplitude and their effect on the average spray cone angle. The experimental results show that periodic cluster of droplets appears at pulsating frequencies up to 4050 Hz when pulsation amplitudes upstream of the injector exceed some critical amplitudes. The frequency of periodic cluster of droplets is the same as pulsating frequencies upstream of the injector. The amplitude of scattered light intensity increases with increasing pulsation amplitude，indicating that the pulsation amplitude of mass flux involved in mixing and combustion process is strengthened. However，the frequency and amplitude of pulsation have little influence on the average spray cone angle with the standard deviation less than 4%.