旋转锥形液膜喷雾形态与表面波动实验研究

Experimental Study of Spray Morphology and Surface Fluctuations of Rotating Conical Liquid Sheet

关键词:  离心喷嘴  锥形液膜  喷雾形态  破碎机理  表面波动

Key words:  Pressure swirl atomizer  Conical liquid sheet  Spray pattern  Breakup mechanism  Surface fluctuation

摘要:

为了全面加深对旋转锥形液膜一次破碎机理的认识，采用高速阴影法对离心喷嘴的喷雾场进行了试验拍摄，并基于喷雾场形态特征详细描述了7种喷雾形态随压降的变化过程，分析了液膜表面波动与液膜穿孔的关系以及导致液膜破碎的机理，重点关注了波动、穿孔和湍流这三种锥形喷雾形态，并对其表面波动特征随压降的变化规律进行了研究。研究表明：液膜的表面波动和液膜穿孔均是由初始速度波动引起的液体聚集从而形成波峰和波谷导致的，在三种锥形喷雾形态中这两种特征一直存在；随着压降增大，在波动锥形喷雾形态中液膜表面波动的波长、振幅和频率均逐渐变大，在穿孔锥形和湍流锥形喷雾形态中液膜表面波动的波长和振幅逐渐减小，频率逐渐增大，且在湍流锥形喷雾形态中，频率组成随压降增大越加混乱。

Abstract:

In order to comprehensively deepen the understanding of the primary breakup mechanism of rotating conical liquid sheet， the spray field of pressure swirl atomizer was experimentally photographed using the high-speed shadowing method. Based on the morphological characteristics of the spray field， the change process of seven spray patterns with pressure drop was described in detail， and the relationship between surface fluctuation and liquid sheet perforation and the mechanism leading to liquid sheet breakup were analyzed， focusing on three conical spray patterns， namely fluctuation， perforation and turbulence， and the change law of their surface fluctuation characteristics with pressure drop was studied. The study shows that the surface fluctuations and perforation of liquid sheet are caused by the aggregation of liquid due to initial velocity fluctuation and thus the formation of wave peaks and troughs， and these two characteristics have always presented in the three conical spray patterns. As the pressure drop increases， the wavelength， amplitude and frequency of the surface fluctuation in the fluctuating conical spray pattern gradually become larger， while the wavelength and amplitude of the surface fluctuation in the perforated conical and turbulent conical spray patterns gradually decrease and the frequency gradually increases， and in the turbulent conical spray pattern， the frequency composition becomes more and more chaotic as the pressure drop increases.