齿筒式齿侧剪切空化器空化性能数值模拟

通过CFD Fluent对齿筒式齿侧剪切空化器进行数值模拟,分析了空化器的齿间涡、空化泡体积分数、湍动能的变化,获得转速、处理量等操作参数对空化器空化性能的影响。结果表明:空化器内的涡是生成空化泡的主要方式。定齿间和动齿间的涡是由于流体冲击壁面,与注入的流体发生回旋而产生的。而齿侧间的涡则是由于双齿侧的机械剪切形成的。充分的机械剪切和剪切面积使得齿侧间的涡分布最广,这表明增加机械剪切可有效诱导空化泡的形成。空化泡溃灭导致齿顶前缘面锐缘处的湍动能增加,并且湍动能随着转速的增加而增加,意味着该空化器既可提高空化泡含量,也可提高空化泡的溃灭率,有效提高了空化性能。但空化泡体积分数随着处理量的增加而减少,空化性能也随之降低。

NUMERICAL SIMULATION RESEARCH ON CAVITATION PERFORMANCE OF THE TOOTH SIDE SHEAR CAVITATOR

In this paper, CFD Fluent was used to carry out a numerical simulation study on the tooth side shear cavitator. The changes in the cavitation between tooth vortex, the volume fraction of cavitation bubbles, and turbulent kinetic energy were analyzed. And the influence of operating parameters, such as rotation speed and processing capacity on the cavitation performance of the cavitator was obtained. The results showed that the vortex in the cavitator was the main way to generate cavitation bubbles. The vortex between the fixed teeth and the movable teeth was generated by the fluid impacting the wall surface and swirling with the injected fluid. However, the vortex between the tooth flanks was formed by the mechanical shear of the two flanks. It meant that sufficient mechanical shearing and shearing area could make the vortex distribution between tooth flanks the widest, indicating that increasing mechanical shearing could effectively induce the formation of cavitation bubbles. The collapse of cavitation bubbles caused the turbulent kinetic energy at the sharp edge of the tooth tip to increase, and the turbulent kinetic energy increased with the increase in rotational speed. It meant that the cavitator could not only increase the content of cavitation bubbles, but also increased the collapse rate of cavitation bubbles, which effectively improved the cavitation performance. However, the volume fraction of cavitation bubbles decreased with the increase of the processing volume, so as the cavitation performance.