俯仰角对水平轴风力机气动噪声影响研究

Influence of pitch angle on aerodynamic noise of horizontal axis wind turbine

由于俯仰角的存在,水平轴风力机在运行时可避免叶片与塔筒的碰撞,但这也对风力机气动噪声的产生及传播带来影响。为探究不同俯仰角对风力机气动噪声的影响规律,文章采用大涡模拟(LES)结合声学方程(FW-H)对不同俯仰角下的风力机声场进行数值模拟。模拟结果表明:随着俯仰角的增大,风轮输出功率先增大后减小,当风轮处在3°俯仰角时,风力机输出功率最大,能量有一个明显扩散,声压级整体有所上升,气动噪声上升幅度变大;存在俯仰角时,气动噪声沿轴向与展向的传播规律与未俯仰时相似,随着俯仰角的增加,最大声源位置从叶中向叶尖移动;A计权下风轮在3°俯仰角时声压级幅值增幅最小,因此3°俯仰角为最佳俯仰角。

The horizontal axis wind turbine can avoid the collision between blade and tower barrel due to the existence of pitch angle in actual operation,but it also affects the generation and propagation of aerodynamic noise of wind turbine.In order to explore the influence law of different pitch angles on aerodynamic noise of wind turbine,large eddy simulation(LES)combined with acoustic equation(FW-H)was used to numerically simulate the sound field of wind turbine under pitch.The results showed that:With the increase of the pitch angle,the output power of the wind turbine firstly increases and then decreases.When the wind turbine is at 3°pitch angle,the output power reaches the maximum,and the energy has an obvious diffusion,the sound pressure level increases overall,and the increase range of aerodynamic noise becomes larger.The aerodynamic noise propagates axially and spanwise in the presence of pitch angle,which is similar to that in the absence of pitch angle.The position of the maximum sound source moves from the middle of the blade to the tip with the increase of pitch angle.The amplitude increase of sound pressure level is the smallest when the wind turbine under the weight is at 3°pitch angle,so it is concluded that 3°pitch angle is the best pitch angle.The research can provide reference for wind turbine operation in pitch state.