基于Comsol Multiphysics的海上风力机塔架模态分析

Modal analysis of offshore wind turbine tower based on Comsol Multiphysics

塔架是风力机的主要支撑装置,鉴于海上特殊的工作环境,塔架振动在所难免。以海上3MW风力机塔架为对象,应用有限元分析软件Comsol Multiphysics对其进行模态分析,除了考虑叶轮激励频率的影响外,还要研究波浪频率对塔架的影响,通过求解有限元特征方程,得到前六阶固有频率及振型,确定引起塔架与外部激励共振主要取决于塔架的低阶频率;摆振是风力机塔架的主要振动,造成塔架顶端振幅较大。通过进行模态分析,为塔架设计、安全运行和结构动力学分析提供更可靠的理论依据。

The tower is a main support device of the wind turbine.Given the special working environment along the offshore,the vibration of the tower is unavoidable.Taking a 3MW offshore wind tower as an example,a modal analysis is carried out by using the finite element software Comsol Multiphysics.Not only the influence of impeller＇s rotation frequency should be considered,but also the effect of wave＇s frequency should be considered.The first six order natural frequency and vibration model are gotten through solving the finite element characteristic equations.Thus it＇s determined that the resonance of tower and external excitation mainly depends on the tower＇s low-order frequency;Shimmy is the main vibration form of the wind turbine tower,which may cause bigger vibration amplitude on top of the tower.It provides theoretic basis for the design and safe operation of the tower and the further dynamic analysis of wind turbine tower through the modal analysis.