自激振荡脉冲喷嘴空化效应及其射流形态的数值分析

发布时间：2018-01-17 12:34

本文关键词：自激振荡脉冲喷嘴空化效应及其射流形态的数值分析　出处：《中国机械工程》2017年13期 　论文类型：期刊论文

【摘要】：基于自激振荡脉冲喷嘴空化效应和多相流模型,建立了自激振荡脉冲射流空化模型。依据自激振荡腔室结构及其几何参数建立了腔室轴对称物理模型,计算得到了振荡周期100ms内自激振荡脉冲射流的空化泡破碎、腔室内两相分布、湍动能分布和速度分布等结果。研究表明:在1.02~2.37ms时,空化泡半径减小,气泡开始径向运动形成泡面加速射流;在2.69~4.67ms时,空化泡面压力达到极限破碎值时气泡开始破碎;在自激振荡周期前25ms,主射流与空气接触边界面形成较强湍动能,自激振荡腔室中心漩涡区逐渐变大,外流场连续射流被割断成多股状射流,射流在喷射轴线附近速度达到并稳定在30~40m/s;在振荡周期的40~90ms,腔室内中心空化气囊形成并开始阻挡主射流运动,喷嘴出口流道出现大面积空化区域,湍动能最大区域集中在下喷嘴出口下游;在振荡后期,随着主射流与空气相互作用及射流贯穿距离增加,主射流速度逐渐趋于稳定且扩散作用减弱。
[Abstract]:Based on cavitation effect of self-excited oscillating pulse nozzle and multiphase flow model, the cavitation model of self-excited oscillating pulse jet is established, and the axisymmetric physical model of the chamber is established according to the structure and geometric parameters of the self-excited oscillation chamber. The cavitation bubble breakup and the two-phase distribution in the cavity chamber were obtained during the oscillation period of 100ms. The results of turbulent kinetic energy distribution and velocity distribution show that the cavitation bubble radius decreases and the bubble starts to move radially to form a bubble surface accelerated jet at 1.02 ~ 2.37 Ms. At 2.69 ~ 4.67 Ms, the bubble begins to break up when the pressure of cavitation surface reaches the limit value. Before the self-excited oscillation period, the turbulent kinetic energy was formed on the boundary surface between the main jet and the air, and the swirl region in the center of the self-excited oscillation chamber gradually became larger, and the continuous jet in the external flow field was cut off into a multi-strand jet. The jet velocity near the jet axis reached and stabilized at 30 ~ 40 m / s; At the oscillation period of 40 ~ 90ms, the cavitation airbag formed in the center of the chamber and began to block the main jet movement, the nozzle outlet channel appeared a large area of cavitation, and the maximum turbulent kinetic energy was concentrated downstream of the lower nozzle outlet. In the latter stage of the oscillation, the velocity of the main jet tends to stabilize and the diffusion decreases with the increase of the interaction between the main jet and the air and the increase of the penetration distance of the jet.
【作者单位】：武汉科技大学机械自动化学院;重庆科技学院机械与动力工程学院;
【基金】：国家自然科学基金资助项目(51405352,51376204)
【分类号】：O358
【正文快照】： 0引言空化是液流系统中由于局部压力低于临界值而诱发液体内部空泡的产生、发展和溃灭的过程,高速射流在进入狭窄的喷嘴内部时往往伴随着复杂的湍流运动和介质密度的变化,极易形成空化[1-2]。研究表明:当空化泡破碎时,泡面微射流瞬间可达到高速、高压和高温的状态。当喷嘴内部

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