浅水效应对螺旋桨轴承力的影响分析

Analysis of propeller bearing force characteristics in shallow water

为了分析浅水条件对螺旋桨轴承力的影响,本文采用RANS方法和VOF模型,对计及自由液面的KCS船桨舵一体系统开展了不同吃水条件下螺旋桨非定常轴承力的数值预报分析。首先计算了深水(h/T=20)工况下的螺旋桨轴承力,通过与试验结果对比,验证了网格划分方法和计算方法的可行性。然后在此基础上进行了不同吃水工况下螺旋桨非定常力计算,监测发现螺旋桨非定常轴承力随时间周期性脉动,浅水条件下螺旋桨轴承力时均值明显大于深水工况。经快速傅里叶变换得到轴承力脉动幅值,分析得出:当h/T<3时,脉动幅值随水深增加迅速减小;当h/T>3时,水深变化对脉动幅值影响较小。

In order to analyze the characteristics of propeller bearing force in shallow water,the RANS meth⁃od and VOF model were adopted and the numerical prediction of propeller bearing force in shallow water was made.Firstly,the propeller bearing force in deep water(h/T=20)was calculated,and the computation results are in good agreement with the experimental results,which validate the feasibilily of the mesh generation method and the calculation method.Based on that,the effect of water depth on propeller bearing force was calculated by changing the water depth.According to the monitoring data,it is found that the unsteady bear⁃ing force is fluctuating periodically over time and the propeller’s time-average value in shallow water is far greater than that in deep water.The frequency spectrum curves are also provided after fast Fourier transform.By analyzing the frequency spectrum data,it is shown that when h/T<3,the fluctuation amplitude decreases rapidly with the increase of water depth,while h/T>3,the change of water depth has little influence on the fluctuation amplitude.