单液滴内空化气泡的生长及溃灭研究

发布时间：2018-12-18 01:10

【摘要】：超空化燃油射流使得喷雾中部分燃油分裂液滴内含有空化气泡;空化气泡的生长及溃灭对液滴的分裂与雾化具有重要影响.基于VOF方法首次对超空化条件下燃油液滴内空化气泡的生长及溃灭过程进行了数值模拟.通过研究发现,单液滴内空化气泡的生长过程可以按控制机理划分为表面张力控制阶段、综合竞争阶段和惯性力控制阶段;在第I阶段,空泡的生长主要受表面张力的控制作用,惯性力对空泡生长的促进作用及黏性力对空泡生长的抑制作用可以忽略;在第II阶段,空泡的生长受表面张力、惯性力及黏性力三者的综合作用,空泡的生长速率是促进空泡生长的惯性力和抑制空泡生长的表面张力及黏性力相互竞争、共同作用的结果;在第III阶段,空泡的生长主要受惯性力的控制作用,抑制空泡生长的表面张力及黏性力的作用基本可以忽略.单液滴内空化气泡的溃灭过程由多个溃灭阶段和反弹阶段构成,类似于有阻尼弹簧振子的振动过程;根据每个溃灭周期结束时空泡半径随时间的变化历程,可以将空泡的溃灭分为快速溃灭期、缓慢溃灭期以及稳定期;溃灭初期空泡溃灭压力的变化非常剧烈,但空泡溃灭体积的变化则要相对平缓得多;空泡反弹压力随时间的变化与空泡反弹体积随时间的变化基本对应.
[Abstract]:Supercavitation fuel jet causes cavitation bubbles in some fuel droplets in the spray, and the growth and collapse of cavitation bubbles have an important effect on the splitting and atomization of droplets. The growth and collapse process of cavitation bubbles in fuel droplets under supercavitation conditions were first simulated based on VOF method. It is found that the growth process of cavitation bubbles in a single droplet can be divided into three stages according to the control mechanism: surface tension control stage, integrated competition stage and inertial force control stage. In the first stage, the growth of cavitation is mainly controlled by the surface tension, and the effect of inertia force on the growth of cavitation and the inhibition of viscous force on the growth of cavitation can be neglected. At the stage of II, the growth of cavitation is affected by surface tension, inertia force and viscosity force. The growth rate of cavitation is a kind of inertia force to promote the growth of cavitation and the surface tension and viscosity force to restrain the growth of cavitation. The result of the joint action; In the III stage, the growth of cavitation is mainly controlled by inertial force, and the effects of surface tension and viscosity force on the growth of cavitation can be neglected. The collapse process of cavitation bubbles in a single droplet consists of several collapsing stages and a rebound stage, which is similar to the vibration process of a damped spring oscillator. According to the changing course of bubble radius with time at the end of each collapse cycle, the bubble collapse can be divided into three stages: fast collapse period, slow collapse period and stable phase. The change of cavitation collapse pressure in the initial stage of collapse is very sharp, but the change of cavitation collapse volume is much more gentle, and the change of cavitation rebound pressure with time corresponds to the change of cavitation rebound volume with time.
【作者单位】：北京交通大学机械与电子控制工程学院;
【基金】：国家自然科学基金(5127601) 国家高技术研究发展计划(2013AA065303) 北京市自然科学基金(3132016) 中国博士后科学基金(2016MS9106) 中央高校基本科研业务费专项资金(2016JBM049)资助项目
【分类号】：O35

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