喷水推进器内非定常压力脉动特性

Pressure fluctuation of unsteady flow in waterjet

基于RANS方程和SST湍流模型,对喷水推进器内非定常流场进行数值模拟.经网格无关性分析后,计算得到的功率、推力与试验值对比最大误差小于4%.分析了设计转速工况和自航工况时叶轮进口、叶轮出口、导叶中部和导叶出口压力脉动的时域和频域特性.结果表明:喷水推进器内最大压力脉动发生在叶轮进口;受不均匀来流影响,叶轮进口从80°至140°半径方向的压力脉动较大;在叶轮进口与出口处,压力脉动主要受叶轮叶频控制,从轮毂到轮缘脉动幅值逐渐增大;设计转速条件下,喷水推进器运行于设计航速工况时叶轮进口压力脉动最小;自由航行时,压力脉动频率与喷水推进器转速呈线性关系,脉动幅值随航速增加而升高.

Based RANS equations and SST turbulent model,the unsteady flow in waterjet was numerically simulated. The mesh independence analysis shows that calculated power and thrust are well consistent with experiment data with maximal error less than 4%. Under the conditions of rated-rotational-speed and self-propulsion, the time-domain and frequency-domain of pressure fluctuation at inlet and outlet of im-peller, middle and outlet of stator were investigated. The results show that the maximum amplitude of pressure fluctuation appears at impeller inlet. The pressure fluctuation at impeller inlet from 80° to 140° radial direction is higher than that at other locations due to the non-uniform inflow. At both inlet and out-let of impeller, the peak frequency occurs at impeller blade passing frequency with fluctuation amplitude gradually increasing from hub to tip. Under the rated-rotational-speed conditions, pressure fluctuation at impeller inlet of rated-ship-speed is the weakest. Under the self-propulsion conditions, peak frequency and waterjet rotational speed present a linear relationship, and the pressure fluctuation intensity is in-creased with the ship speed.