基于改进延迟分离涡方法的潮流能水轮机纵摇运动水动力分析

HYDRODYNAMIC ANALYSIS OF PITCH MOTION OF TIDAL CURRENT TURBINE BASED ON IMPROVED DELAYED DETACHED EDDY SIMULATION METHOD

为探究强迫纵摇运动对浮式潮流能水轮机水动力性能的影响,该文基于改进延迟分离涡模型(IDDES)与滑移网格技术相结合的方法,建立了浮式潮流能水轮机旋转和纵摇耦合运动的CFD数值模型。首先选取潮流能水轮机的水槽试验结果来验证所建立的数值模型的计算精度,其次在不同纵摇频率和纵摇幅值下,对浮式潮流能水轮机开展三维非定常模拟。研究结果表明:(1)水轮机水动力系数(能量利用率系数和轴向载荷系数)的整体波动频率为纵摇频率的两倍,同时伴随着频率为叶轮转频的高频脉动;(2)随着纵摇频率的增加,水轮机平均水动力系数略有增加,而随着纵摇幅值的增加,其平均水动力系数略有减小,但均小于无纵摇工况下的平均水动力系数;(3)在纵摇最大振幅位置处,水轮机各叶片迎流面承受不同程度的水压载荷。纵摇运动对平衡位置和最大振幅位置处的尾迹均有影响,且尾迹出现较为明显的低速区摆动现象。

In order to explore the effect of forced pitch motion on the hydrodynamic performance of the floating tidal current turbine,a CFD numerical model of rotation and pitch coupling motion of the floating tidal current turbine is established based on the combination method of improved delayed detached eddy simulation(IDDES)and sliding mesh technology.Firstly,the flume test results of the tidal current turbine are selected to validate the calculation accuracy of the established numerical model.Secondly,the three-dimensional unsteady simulation of the floating tidal current turbine is carried out under different pitch frequencies and pitch amplitudes.The research results show that:(1)The overall fluctuation frequency of the hydrodynamic coefficient(energy utilization coefficient and axial load coefficient)of the turbine is twice the pitch frequency,accompanied by the high-frequency pulsation whose frequency is the rotation frequency of the rotor;(2)With the increase of pitch frequency,the average hydrodynamic coefficient increases slightly,while with the increase of pitch amplitude,the average hydrodynamic coefficient decreases slightly,but they are less than the average hydrodynamic coefficient without pitch motion;(3)At the position of the maximum pitch amplitude,the upstream surface of the turbine blade bears different degrees of hydraulic load.The pitch motion has an effect on the wake at the equilibrium position and the maximum amplitude position,and the wake has a relatively apparent low-speed swing phenomenon.