强湍流相干结构对偏航风力机叶根载荷的影响

Effects of strong turbulence structure coherent on load of blade root in a yaw wind turbine

强湍流风对偏航状态风力机叶片的动态载荷会产生显著影响,叶片根部载荷的动态特性是影响风力机使用寿命和安全运行的关键因素。该研究采用NWTCUP(The NREL National Wind Technology Center Model)风谱模型耦合KHB(Kelvin-Helmholtz Billow)流动,构建了一种强湍流相干结构风况,利用FAST(Fatigue,Aerodynamics,Structures and Turbulence)程序计算了该风况下NREL 1.5 MW风力机在不同偏航角下的气动载荷,研究了KHB湍流相干结构对偏航状态下风力机叶根动态载荷的影响。研究表明,湍流相干结构会使风力机载荷的波动幅值和能量增加。偏航角的增大对叶根摆振力矩影响较小,但对叶根挥舞力矩影响较大,并使二者波动程度增强。湍流相干结构使叶根摆振力矩的最大值、标准差平均升高28.30%和0.64%,最小值和平均值平均降低27.28%和1.903%,叶根挥舞力矩的最大值、标准差和平均值平均升高36.27%、59.57%和2.906%,最小值平均降低114.83%。叶根载荷的小波分析表明,湍流相干结构对摆振力矩频域能量影响较小,且能量主要集中在低频段并与雷诺应力的剪应力分量(u′w′、v′w′)对应较好;对叶根挥舞力矩频域能量影响显著,且能量变化与雷诺应力的剪应力分量(u′w′)对应较好,随着偏航角的增大,叶根挥舞力矩频域能量整体升高。对叶片根部进行加固则可以有效提升叶片的使用可靠性。

The strong turbulent wind has a significant impact on the dynamic load of wind turbine blade in a yaw state.Because the root of blade is the most stressed position,the dynamic characteristics of load are the key factors affecting the life and safe operation of wind turbine.In this study,the NWTCUP(The NREL National Wind Technology Center Model)wind spectrum model was used to couple KHB(Kelvin-Helmholtz Billow)flow,in order to construct a strong turbulent coherent structure wind condition.Subsequently,the FAST(Fatigue,Aerodynamics,Structures,and Turbulence)program was used to calculate the aerodynamic load of the NREL 1.5MW wind turbine under different yaw angles.Finally,the effect of KHB turbulent coherent structure was investigated on the dynamic load of wind turbine blade roots under yaw conditions.The results showed that the turbulent coherent structures increased the amplitude and energy of load fluctuations in a wind turbine.The increase of yaw angle has a smaller effect on the blade root edgewise moment,while a greater effect on the blade root flapwise moment,indicating the stronger dispersion of both factors.The turbulent coherent structure reduced the average value of blade root edgewise moment by 1.903%,while increased the average value of blade root flapwise moment by 2.906%.In Wavelet analysis of the root load,the turbulent coherent structure has a small effect on the energy of the edgewise moment,while,the energy was mainly concentrated in the low frequency band,corresponding to u'w',v'w'.There was a significant effect in terms of the leaf root flapwise moment,where the energy change corresponds well with u'w'.The energy of leaf root flapwise moment increased,as the yaw angle increased.