不同收缩角下伞形风力发电机的模态分析

为了真实反映出伞形风力发电机在不同风速、不同收缩角(0°,30°,45°,60°)下的振动情况,借助ANSYS平台中的Modal模块对5kW伞形风力发电机进行有预应力的模态分析.将气动力、离心力、重力作为边界条件,模拟计算伞形风力发电机整机的前六阶模态变化与相应形变,并对整机在定风速和定转速情况下,一阶模态固有频率随收缩角的变化规律进行研究.分析结果显示,伞形风力发电机的固有频率和风轮工作频率、风轮3倍工作频率的相对差值分别为57.2%,-90.5%,可以完全避开共振,其设计是合理的;随着收缩角的增大,一阶固有频率减小,且转速对一阶固有频率的影响程度比风速大;摆振是低频区的主要振动形式,挥舞和扭转振动多出现在高频区;随着风速增大风力机的前六阶模态频率变化平稳,但随转速的增加上升幅度明显,而且离心力比气动力对风力机的动频影响作用更大.

Modal analysis of umbrella wind turbine under different shrinkage angles

In order to truly reflect the vibration of umbrella wind turbines at different wind speeds and different shrinkage angles(0°,30°,45°,60°), the prestressed modal analysis of the 5kW umbrella wind turbine is carried out with the help of the Modal module in the ANSYS platform. Taking the aerodynamic force, centrifugal force and gravity as the boundary conditions, were the first six modality changes and the corresponding deformations of the umbrella wind turbine simulated and calculated. In the case of constant wind speed and constant revolving speed, the natural frequency of the first-order modality with the angle of contraction changes regulation is studied. The analysis results show that the relative difference between the natural frequency of the umbrella wind turbines and the operating frequency of wind turbines and the three times operating frequency of wind turbines are 57.2% and -90.5% respectively, which can completely avoid resonance and its design is reasonable.With the increase of the shrinkage angle, the natural frequency of the first-order decreases and the influence of the rotating speed on the natural frequency of the first order is greater than that of the wind speed. The shimmy is the main form of vibration in the low frequency region. The flapping and torsional vibrations are mostly in the high frequency region. The first six modes of the wind turbine change smoothly with the increase of the wind speed, but the increase rate with the increase of the rotational speed is ob-vious, and the centrifugal force ratio against aerodynamic forces has a greater impact on the dynamic frequency of wind turbines.