双赫姆霍兹复合喷嘴空化腔特性数值模拟

Numerical simulation of cavitation cavity characteristics of double Helmholtz nozzle

基于自振频率更高的赫姆霍兹型喷嘴设计了双赫姆霍兹型脉冲空化射流喷嘴,通过数值模拟分析了谐振腔腔比、腔距、腔间中流道直径和圆角半径对其空化效应、湍流动能、出口速度等特性的影响。结果表明,谐振腔腔比、腔距、腔间中流道直径和圆角半径的改变均会影响喷嘴内部空化效果。当谐振腔腔比为0.84,腔距为40 mm,腔间中流道直径为12 mm时,两个谐振腔内空化泡生成效果好,腔内含气率高,喷嘴出口湍流动能强,进而更利于脉冲空化清洗效率的提高。当对喷嘴两个腔室入口进行圆角处理时,喷嘴内部空化程度下降,湍流动能降低,抑制了喷嘴的空化脉冲性能,对改善喷嘴清洗效应具有反作用。

Based on the Helmholtz nozzle with higher natural frequency,a double Helmholtz pulse cavitation jet nozzle is designed.The effects of the cavity ratio,cavity distance,flow path diameter and fillet radius between the two resonators on their cavitation effect,turbulent kinetic energy and outlet velocity characteristics are analyzed by numerical simulation.The results show that the change of cavity ratio,cavity distance,flow path diameter and fillet radius will affect the cavitation effect in the nozzle.When the cavity ratio of the resonant cavity is 0.84,the cavity distance is 40 mm,and the flow path diameter between the cavities is 12 mm,the cavitation bubble generation effect in the two resonant cavities is good,the cavity void fraction is high,and the turbulent kinetic energy at the nozzle outlet is strong,which is more conducive to the improvement of the pulse cavitation cleaning efficiency.When the two chamber inlets of the nozzle are rounded,the internal cavitation of the nozzle decreases dramatically and the turbulent kinetic energy decreases,which inhibits the cavitation pulse performance of the nozzle and has a reaction to improve the nozzle cleaning effect.