液压节流阀内非定常空化特性的数值分析

基于修正的RNG k-ε湍流模型并结合Schnerr-Sauer空化模型及多相流模型对液压节流阀内部非定常空化流动进行了数值计算，分析了节流阀内空化形态的周期性变化过程及其对应的内部流场的压力脉动特性，讨论了非定常空化形态演变与压力脉动之间的关系，同时研究了不同空化阶段对节流阀内速度场的影响差异。结果表明：节流阀内空化的发展是一种非定常的周期性过程，主要包括空化的产生、脱落以及溃灭；在空化初生时，不同位置截面在轴向速度分布上均未出现反向射流，但在空化溃灭阶段，不同位置截面在靠近壁面处均存在一个宽度大约1mm的反向射流区，且不同截面位置所对应的反向射流的强度不同；阀口下游不同监测点处压力脉动的主频与空化结构演化的周期有着良好的一致性，此外还存在一个次级频率，对应为小尺度空化脱落、溃灭的频率。
Abstract：Based on the modified RNG k-ε turbulence model combined with Schnerr-Sauer cavitation model and the multiphase flow model, unsteady cavitation flow in throttle valve was numerically calculated.The periodic variation process of unsteady cavitation form in throttle valve and the corresponding inner flow field’s pressure fluctuation characteristics were analyzed.The relation between unsteady cavitation form evolution and pressure fluctuation was explored.Meanwhile, the differences among influences of different cavitation stages on velocity field in throttle valve were studied.The results showed that the development of cavitation in throttle valve is an unsteady periodic process mainly including cavitation generation, shedding and collapse; at the beginning of cavitation, backward jet does not appear for different positions’ sections in axial velocity distribution; but in the stage of cavitation collapse, different positions’ sections have a backward jet range with the width of about 1mm near the wall, the backward jet intensities corresponding to different positions’ sections are different; the main frequency of pressure fluctuation at different monitored points in the valve port downstream agrees well with the evolution frequency of cavitation structure; in addition, there is a secondary frequency corresponding to that of small scale cavitation shedding and collapse.