基于体积力法的全附体KCS型船模PMM运动数值模拟

Numerical simulation on planar motion mechanism of KCS ship model with a body-force propeller model

为高效、精确地求解船舶操纵水动力导数,以全附体KCS型船模为研究对象,基于RANS方程及VOF模型,在star-ccm+平台上采用体积力法模拟螺旋桨作用,计及自由面兴波及航行姿态变化对船模水动力的影响,开展斜航、纯艏摇、漂角和艏摇组合3种平面运动机构(Planar Motion Mechanism,PMM)运动的数值模拟,将横向力Y、艏摇力矩N、横倾力矩K的数值模拟结果与试验结果进行对比,并依照PMM试验的动力学方程,通过最小二乘法拟合和傅立叶积分,将数值模拟结果与试验结果的时历曲线进行分析处理,求得操纵水动力导数。研究结果表明:该方法用于数值模拟PMM运动是可行的;求得的水动力导数中Y′vvv,N′vvv误差略大,其余水动力导数误差均在15%以内。

In order to solve the ship maneuvering hydrodynamic derivatives efficiently and accurately,full-appendage KCS ship model is taken in this paper as the studying object. Based on RANS equation and VOF model, a descriptive body-force model is established to represent real propellers on the star-ccm+;the influences of the free surface wave and motion attitudes change on hydrodynamic are taken into account. The oblique motion, the yaw motion, the combination of yaw and drift angle motion on Planar Motion Mechanism(PMM)are simulated, and the athwartship force Y, the yawing moment N, and the heeling moment K are also acquired. The simulation results are then compared with the actual test results: according to the dynamics equation of PMM test, the time history curves of numerical and experimental results are analyzed with least-squares fitting and Fourier integral, where the hydrodynamic derivatives of manipulation are finally obtained. The results demonstrate the feasibility of the proposed method in PMM simulation,though the errors of Y′vvv and N′vvv are slightly larger, the errors of remaining hydrodynamic derivatives are all below 15%.