本研究探討垂直軸風力渦輪機之聲學特性，利用ANSYS FLUENT計算風力機周邊之流場，並使用其Acoustics Model進行聲學模擬，氣動聲學之理論中藉由FW-H 方程式，風力機葉片上之速度與壓力可選為聲源，其物理意義為單極子與偶極子；此外由permeable FW-H 方程式，聲源可為包含葉片與紊流流場之流體介面，意義為包含單極子、偶極子與四極子的影響，並針對不同聲源設定，在不同風速、轉速下進行模擬。 由數值結果發現在不包含塔架的模擬中，最大聲壓位準發生在人耳無法接收的葉片通過頻率上；此外由紊流產生的寬頻噪音則發生在200Hz至500Hz，隨轉速而上升，且紊流寬頻噪音為風力機主要的噪音源。此外在包含塔架的模擬中，最大聲壓位準之發生頻率仍隨轉速而上升。此項研究可提供研究人員一套模擬方法，有助於分析風力之氣動噪音，並幫助風力機開發與設計。 In this study, the aeroacoustic characteristics of a small vertical axis wind turbine are analyzed by using ANSYS FLUENT. The FW-H theory with a permeable surface is chosen for formulation. The pressure and the velocity on the rotating blades surface provide the monopoles and dipoles while turbulences surrounding the blades give the quadrupole effect. Then, the aeroacoustic noise due to the rotating wind turbine are investigated for different wind speeds and rotating frequencies. For a simple model of blades with or without considering the supporting tower, the numerical results show that the maximum sound pressure, due to blade rotating, usually occurs at the blade passing frequency although it is in the subsonic region. There is additional broadband noise, resulted from turbulences, near the frequency region 200Hz to 500 Hz. Actually, the broadband noise dominates the sound from a turbine. The maximum sound pressure level and its corresponding frequency usually increase with rotational frequency.
