风力机冰脱落轨迹仿真研究

Numerical Simulation of Ice Shedding from Wind Turbine

风力机叶片上所结的冰会随着桨叶的转动而发生脱落。冰脱落过程受到风力机复杂流场的影响,并且在运动过程中冰的转动也会对其位移无法控制。针对上述问题,提出将风轮所在的平面简化为致动盘得到风力机流场;将冰粒视为片状刚体,在分析其受力的基础上基于牛顿运动学第二定律和动量矩定理建立了风力机冰粒脱落的四自由度轨迹模型,并嵌入了气动阻尼的影响。将本文数值仿真结果与实验进行对比以验证所用方法的正确性。最后计算并分析了不同尺寸、不同初始姿态角和气动阻尼对风力机结冰脱落轨迹和范围的影响。结果表明:冰粒尺寸越大、气动阻尼系数越大,运动范围越小;而初始姿态角对冰粒运动的影响较为复杂。改进方法对未来的风力机布局有着重要的指导意义。

Ice accreted on the wind turbine blade will shed due to the rotation of the blade. The ice shedding process is affected by the complex flow field around the turbine, and the ice displacement is also affected by the rota- tion of the ice crystal. In this study, the plane of the wind turbine was regarded as an actuator disc such that the N - S equations of the flow field were calculated, and the ice crystal was regarded as flaky rigid body, whose actual mo- tion was reasonably simplified. Based on Newton＇s second law of kinematics and the theorem of momentum, a four - degree of freedom trajectory model was proposed to simulate the ice shedding process. The effect of the aerodynamic damping was also taken into consideration. Simulation results were compared with experimental ones, and the validity of the method was proven. The effects of size, initial angle and aerodynamic damping on the trajectory of the flaky ice crystals were analyzed. Results show that the range of motion gets smaller with bigger size and coefficient of damping, while the influence from the initial angle is rather complicated. The above method can serve as a basis for the arrangement design of wind turbines in the future.