Numerical analysis for unsteady cavitation characteristics in throttle valve

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. © 2019, Editorial Office of Journal of Vibration and Shock. All right reserved.