摘要
风琴管射流的空化作用虽由其振荡特性诱发,但受制于其出口结构,出口结构对空化作用的影响一直被忽视。首先从射流空化作用机理出发,分析风琴管喷嘴出口边界层流动特性,揭示喷嘴出口结构与空化作用的内在联系。基于水声学原理,采用噪声信号分析法研究了相同空化数下出口结构参数对风琴管射流空化作用的影响,探究不同空化数下出口结构参数对射流空化作用的影响规律。试验结果表明,流道长度L1、扩口长度L2及扩口角度θ等喷嘴出口结构参数对射流空化作用效果均产生显著影响,L1仅对射流空化作用产生直接影响,L2仅对射流空化作用产生间接影响,而θ对射流空化作用产生双重影响;L1、L2及θ对射流空化作用的影响具有明显的规律性,均存在合理的取值范围,在该范围内射流空化作用效果较佳。风琴管射流的高频振荡特性只是自振射流发生空化作用的前提条件,而喷嘴的出口结构在一定程度上决定着自振射流的实际空化作用效果。
Although cavitation of the organ-pipe waterjet is induced by its oscillation, it depends on the outlet geometry of organ-pipe nozzle, which has been neglected. Based on the cavitation mechanism of the organ-pipe waterjet, the boundary layer flow characteristics through the nozzle outlet are analyzed, then the relationship between the nozzle outlet geometry and cavitatinggeneration is revealed. The effect of the nozzle outlet geometry on jet cavitation under the same cavitation number is investigated using the noise signal method, and its influence under different cavitation numbers is also explored. The experimental results show that the nozzle outlet parameters including the throat length L1, flaring length L2 and flaring angle θ have a significant impact on jet cavitation performance.L1 influences the jet cavitation directly,L2 can only influence the cavitation by the jet oscillation, while θ has a dual effect mentioned above. The effects of these parameters on jet cavitation have obvious trends, and there exist reasonable value ranges, within which the jet has a strong cavitation effect. High-frequency oscillation is just the precondition for the self-resonating waterjet to induce cavitation, while to some extent, the nozzle outlet geometry determines the actual cavitation performance of waterjet.
作者
蔡腾飞
潘岩
马飞
邱林宾
徐平平
CAI Tengfei;PAN Yan;MA Fei;QIU Linbin;XU Pingping(School of Mechanical Engineering, University of Science and Technology Beijing, Beijing 100083)
出处
《机械工程学报》
EI
CAS
CSCD
北大核心
2019年第18期150-156,共7页
Journal of Mechanical Engineering
基金
国家自然科学基金(51774019)
国家“十二五”(DY125-14-T-03)资助项目
关键词
喷嘴
出口结构
风琴管射流
空化作用
空化噪声
nozzle
outlet geometry
organ-pipe waterjet
cavitation
cavitation noise
