高速强湍流风况下的风力机结构动力学响应

Structural Dynamic Response of a Wind Turbine Under High-speed Strong Turbulence Inflow Conditions

为研究大型风力机在高速强湍流风况下的结构动力学特性,基于NWTCUP风谱模型建立平均风速为25m/s的极限湍流三维风场,比例缩放Kelvin-Helmholtz不稳定流的数值模拟结果作为相干结构,将其加入普通湍流风场表示湍流度更强的风况,在FAST软件中分别计算加入相干结构前、后风力机的动力学特性,并仿真偏航30°、紧急顺桨停机和一直顺桨停机3种偏工况,得到各个工况下叶片和塔架载荷的动态响应.结果表明:加入相干结构后,风速在空间及时域的变化均更加剧烈,相干湍动能更大,可表示湍流强度更高的风况;加入相干结构后,风力机动力学响应加剧,其中塔基弯矩影响最大,响应幅值波动变化范围增大了1.96倍;叶片载荷主要刺激频率为风轮旋转频率,塔架响应为塔架一阶侧向振动频率;相干结构对偏工况的影响较大,在偏航和紧急停机等非稳定运行过程中,塔尖弯矩非平稳过程明显.

To analyze the structural dynamic response of large-scale wind turbines operating under highspeed strong turbulence inflow conditions, a three-dimensional extreme turbulence flow field with an aver age wind speed of 25 m/s was established based on NWTCUP wind spectrum. By adding the coherent structures deduced from the scaling numerical results of Kelvin-Helmholtz instable flow to the background wind to represent an inflow condition of higher turbulence intensity, the structural dynamic response of the wind turbine respectively with coherent inflow and normal turbulence flow fields were calculated in FAST code under three off-design conditions, such as yaw to 30°, emergency shutdown and parked cases, etc. Results show that coherent structures enhance the changes of wind speed in space-time domain, with increased kinetic energy of coherent turbulence （CTKE）, suitable for representing the case of higher turbulence intensity; while coherent structures promote the dynamic response of wind turbine, especially on the bending moment of tower base, with the variation range of response amplitude expanded by 1.96 times. The stimulus frequency of root bending load is the frequency of wind wheel rotation, while the response of both tower load and nacelle motion is of the first-order natural frequency of side to side vibration. Coherent structures have greater impact on the tower tip moment under off-design conditions, and the non-stationary fluctuations becomes significant during yawing, emergency shutdown and other non-steady operation periods.