切出风速下大型风力机变桨故障叶片气动及结构特性研究

RESEARCH ON AERODYNAMIC AND STRUCTURAL CHARACTERISTICS OF LARGE-SCALE WIND TURBINE BLADE WITH PITCH FAULT UNDER THE CUT-OFF WIND SPEED

风力机叶片变桨故障极易引发不稳定超高负载而导致结构失效损毁。首先,基于计算流体力学方法对NREL 5 MW风力机变桨故障/成功叶片气动侧特征进行分析,然后,利用双向强流固耦合及屈曲分析对典型方位角下变桨故障叶片状态展开研究。结果显示,切出风速下变桨故障叶片挥舞力矩平均值为变桨成功叶片的13.8倍,且前者流场尾迹更明显。叶片在双向强流固耦合下挥舞力矩较之无流固耦合波动范围明显更广,且变桨故障叶片最大叶尖位移为变桨成功叶片的14.1倍。对于0°、60°、120°和180°四个典型方位角,随角度增大变桨故障叶片的弯矩大小、叶尖位移、弯曲程度、端部效应、尾迹范围和强度逐渐减小。屈曲分析发现随方位角增大,屈曲因子呈递增趋势,其中180°方位角较之0°方位角的一阶屈曲因子增加20.2%。

Wind turbine blade pitch fault is easy to cause unstable ultra-high load,which can lead to structural failure and damage.Firstly,the aerodynamic characteristics of NREL 5 MW wind turbine blades with pitch fault/success were analyzed based on the computational fluid dynamics method.Then,the two-way strong fluid-structure coupling and bending analysis were used to study the state of blades with pitch fault under typical azimuths.The results show that average flapwise torque of the blade with pitch fault under the cut-out wind speed is 13.8 times that of the blade with successful pitch,and the flow field wake of the former is more obvious.The fluctuation range of blade flapwise torque under two-way strong fluid-structure coupling is significantly wider than that without fluid-structure coupling,and the maximum tip displacement of the blade with pitch fault is 14.1 times that of the blade with successful pitch.For the four typical azimuth angles of 0°,60°,120°,and 180°,the bending moment,tip displacement,bending degree,end effect,wake range and strength of the blade with pitch fault gradually decrease with the increase of the angle.Buckling analysis reveals that the buckling factor increases with the enlargement of azimuth angle,and the first-order buckling factor of 180°azimuth is 20.2%higher than that of 0°azimuth.