剪切流下潮流能水平轴水轮机的水动力分析

Hydrodynamic analysis of horizontal axis tidal current turbine under shear flow

为研究剪切流下潮流能水平轴水轮机的水动力问题,本文采用叶素动量理论与动态入流模型相结合的方法,考虑相对入流速度的时域变化,计算了不同剪切率下水轮机的各水动力系数,探究了剪切率对潮流能水平轴水轮机的水动力载荷特性的影响规律。经验证,数值模型与CFD模拟结果吻合良好。结果表明:一定范围内,同一速比下,剪切率对时均轴向力系数的影响不明显,对时均功率系数的影响大约以最优速比为分界,高速比时剪切率越大,功率系数越大,低速比时关系不明显;水动力系数的波动周期与叶轮旋转周期存在倍数关系;水动力系数的幅值与剪切率呈近似线性关系。本文可为剪切流下潮流能水平轴水轮机的载荷分析、设计优化提供有效的预报。

Given the change in the time domain of the relative inflow velocity,hydrodynamic coefficients at different shear rates are calculated by combining the blade element momentum theory and dynamic inflow model to study the hydrodynamic problems of a horizontal-axis tidal current turbine(HATCT)under shear flow.The influence law of shear rate on the hydrodynamic load characteristics of HATCT is also studied.The results verified that the numerical model is in good agreement with CFD simulation results.Under the same tip speed ratio(TSR)within a certain range,the influence of shear rate on the time-averaged thrust coefficient is not evident.Meanwhile,the influence on the time-averaged power coefficient is divided by the optimal TSR;the greater the shear rate at high TSR,the greater the power coefficient.However,this relationship is not evident at low TSR.Multiple relationships are observed between the period of hydrodynamic coefficients and the rotation period of the rotor.The amplitudes of hydrodynamic coefficients are approximately linear with shear rates.These results provide an effective prediction for the load analysis and design optimization of HATCT under shear flow.