本篇文章主要目地為探討轉軸系統在旋轉時所產生的振動與噪音問題。首先建立轉軸的振動方程式，本文以漢米爾頓定理做為基礎，推導得轉軸系統之運動方程式，系統之外力可由週期性外力模擬之，再導入格勒金法，進而求取位移近似解。接著考慮噪音的部分，轉軸系統於運動過程中，系統之振動造成附近空氣分子擾動，此擾動現象即可產生氣動噪音，亦是本文所探討之要點。對於此現象本研究引用萊特希爾所提出之理論，並由Ffowcs Williams與Hawkings延伸而得的氣動聲學理論，進行轉軸系統周圍的聲場計算，並藉由分析、討論來瞭解系統之特性。 This article focuses on vibration and noise prediction of a rotating beam. The governing equations of a rotating beam, subjected to a periodic point force, are first established by using the Hamilton’s principle and Galerkin’s method. Then, the displacement is solved. Aerodynamic theory, introduced by Lighthill and improved by Ffowcs Williams and Hawkings, can be used for predicting the developed noise of a body in motion. The noise of the rotating beam is calculated based on this theory. Parameter studies are presented.
