复杂大气入流下海上风机力学特性研究

随着风能技术的不断进步, 风机叶片逐渐向大型化发展, 这使得真实复杂大气入流对风机运行性能的影响愈发显著. 为研究真实复杂大气入流下海上风机的力学特性响应, 利用基于大涡模拟的域前模拟方法生成复杂大气入流, 并结合致动线模型模拟风机叶片, 对中性复杂大气入流下海上固定式风机进行数值模拟, 重点分析风机的气动性能及转子和叶片根部的力学特性, 并与均匀入流计算工况进行对比. 计算结果表明, 中性复杂大气入流中的大尺度低速气流团使得风机气动功率输出值在较长一段时间处于较低水平, 此外, 中性复杂大气入流的高湍流强度特征使得风机气动功率的变化幅值和标准差较均匀入流工况大幅增加; 风机轴向推力的标准差值增加到均匀入流的53倍, 中性复杂大气入流的来流流场扰动引起偏航力矩的最大值、均方根和标准差分别增加到均匀入流的10、4.4和4.3倍; 速度垂向分布的不均匀性以及轮毂高度附近的大尺度低速羽流结构导致摆振剪力和弯矩的标准差响应值分别为均匀入流的2倍和4.6倍. 

NUMERICAL STUDY OF DYNAMIC CHARACTERISTICS FOR OFFSHORE WIND TURBINE UNDER COMPLEX ATMOSPHERIC INFLOW1)

With the great development of wind energy technology, the blades of wind turbine have gradually developed to large-scale, which makes the real and complex atmospheric inflow have more and more significant impacts on the operating performance of wind turbines. The numerical simulation of bottom-fixed offshore wind turbine under neutral complex atmospheric inflow is performed to study the dynamic responses of wind turbine under that complex inflow. A precursor simulation method based on large eddy simulations is used to generate the complex atmospheric inflow, and the actuator line model is combined to model the wind turbine blades. The numerical results are compared with the uniform inflow condition, and the results are focusing on the analysis of aerodynamic performance and the dynamic characteristics of rotor and blade root. The numerical results show that the large-scale low-velocity airflow in the neutral and complex atmospheric inflow is responsible for the lower output of wind turbine aerodynamic power in a long period time. In addition, the high turbulence intensity characteristics of the neutral and complex atmospheric inflow lead to the significant increase of varying amplitude and standard deviation of wind turbine aerodynamic power. The standard deviation of rotor thrust increased to 53 times of the uniform inflow condition, and the maximum value, root mean square and standard deviation of yaw moment increased to 10, 4.4 and 4.3 times of uniform inflow condition, because of the disturbance of the neutral and complex atmospheric inflow. The standard deviation values of flapwise shear force and bending moment reach up to 2 and 4.6 times of uniform inflow condition, respectively, caused by the collective effects between the inhomogeneity of the velocity vertical distribution and the large-scale low-velocity plume structures near the hub height.