以流固耦合模擬探討風機葉片之渦流誘發振動

Abstract

風力發電近年快速增長使的全球各地增加了大量的風機設施及裝置，而風力機葉片常由柔韌的複合材料製成，並需面對複雜風況對其結構強度與疲勞的考驗，本研究使用Ansys多物理工程模擬軟體探討渦流及葉片的流場與雙向流固耦合關係。本文研究首先透過Ansys Fluid Flow(Fluent)進行流場之架設與模擬，並加入Ansys Transient Structural做為固體之運算模組以及System Coupling模組構建雙向流固耦合之模擬，通過三種不同流速驗證渦流誘發振動帶動短葉片之鎖定(lock-in)效應，並針對葉片入流的攻角所造成之影響進行呈現。模擬結果顯示在流場分析中，渦流逸散頻率與理論值比較誤差極小，並且在雙向流固耦合運算中，成功重現渦流誘發振動引起的鎖定現象，得出如共振般持續放大的週期性位移，也重現了不同入流攻角下的渦流逸散與渦流誘發振動現象，在10 m/s流速下僅在入流接近垂直時觀察到鎖定現象，而渦流逸散現象在葉片和入流方向夾角超過 的範圍較為顯著，在入流方向與葉片接近平行時則會減弱甚至消失。然而本文的設定從入流設定到模型架設皆進行了一定程度的簡化以在現今的設備下順利進行研究，若能擴增運算資源或結合如大數據及人工智慧等技術，研究主題將能進一步深化並有更廣泛的應用。

The rapid growth of wind power generation in recent years has led to the installation of numerous wind turbine facilities worldwide. Wind turbine blades are typically made of flexible composite materials and must withstand complex wind conditions caused by external environmental factors such as weather, wind direction, and rotation, which pose challenges to their structural strength and fatigue. This study uses Ansys multiphysics simulation software to investigate vortices at smaller scales and the fluid-structure interaction (FSI) of wind turbine blades. The study first uses Ansys Fluid Flow (Fluent) to set up and simulate the flow field, incorporates Ansys Transient Structural for solid computation, and employs the System Coupling module to construct a 2-way FSI simulation. Three different flow speeds are tested to validate the lock-in phenomenon induced by vortex-induced vibrations on short blades, and the impact of the blade's angle of attack on inflow is presented. The simulation results show that the vortex shedding frequency in the flow field analysis matches the theoretical values. The 2-way FSI simulation successfully recreated the lock-in phenomenon caused by vortex-induced vibrations, resulting in periodic displacements akin to resonance. Different inflow angles also influenced vortex shedding and induced vibrations, with lock-in observed only when the inflow was nearly perpendicular at a flow speed of 10 m/s, and the vortex shedding phenomenon is more pronounced when the angle between the blade and the inflow direction exceeds , while it weakens or even disappears when the inflow direction is nearly parallel to the blade.. However, the study's setup involved some simplifications to proceed with current resources. Expanding computational resources or integrating big data and artificial intelligence technologies could further deepen the research and broaden its applications.