以聲學類比方法預測螺槳噪音

Prediction of underwater noise from a marine propeller by acoustic analogy

許文彥(Wen-Yen Hsu)

指導教授 ： 黃維信

國立臺灣大學/工學院/工程科學及海洋工程學研究所/碩士(2018年)

https://doi.org/10.6342/NTU201803878

摘要

本文係以經由雷諾平均方程(RANS)的軟體計算出的螺槳流場作為發出聲壓訊號的聲源，並為了使其有時間上的變化，將場點上的速度、壓力旋轉平移以模擬出螺槳在流場中推進的效果，再使用Ffowcs Williams-Hawking(FW-H)聲學類比的演算法對其進行計算。其中，使用了有限差分法(Finite Difference Method)與數值積分法取代了FW-H聲波方程中的微分項與積分。為了驗證演算法的可靠性，本文以點源流建立了假想的無黏流場函數代入演算法中，以驗證數值方法的準確性。在計算螺槳流場引起的聲壓時，將計算螺槳在流場中旋轉時場點上聲源強度的分布，以探討與螺槳流場的聲壓變化的關係，並討論聲壓在近場與遠場之間的差異。

關鍵字

螺槳 ； Ffowcs Williams-Hawking聲學類比 ； 有限差分法 ； 數值積分法 ； 聲壓 ； 聲源強度

並列摘要

The objective of this thesis is to simulate the acoustic pressure field of a marine propeller. The flow field of a marine propeller is generated by software based on RANS. The method for calculating acoustic pressure used in this thesis is based on Ffowcs Williams-Hawking(FW-H) analogy. The partial differential and integral terms in FW-H acoustic wave equation are substituted with Finite difference method and Numerical integration. Besides, this thesis uses an inviscid flow field function generated by point source to verify the method reliability based on FW-H. When calculating the acoustic pressure of marine propeller, the relationship between sound pressure and distribution of sound source strength is investigated. The difference of sound pressure for far field and near field is discussed.

並列關鍵字

Marine propeller ； Ffowcs Williams-Hawking analogy ； Finite Difference Method ； Numerical integration ； Acoustic pressure ； sound source strength

參考文獻

[1]汪玉, 世界海軍潛艇, 國防工業出版社, 北京, 2007

[2]Lighthill, M. J., “On the sound generated aerodynamically. Part I: General theory”, Proceeding of the Royal Society of London A, 211, pp. 321-342, 1952

[3]Curle, N., “The Influence of Solid Boundaries upon Aerodynamics Sound”, Proceeding of the Royal Society of London A, 231, pp. 505-514, 1955

[4]Ffowcs Williams, J. E. and Hawkings, D.L., “Sound Generation by Turbulence and Surfaces in Arbitrary Motion”, Philosophical Transactions of The Royal Society A, Mathematical Physical and Engineering Sciences, 264, pp. 321-342, 1969

[5]Farassat, F. and Succi, G. P., “A review of propeller discrete frequency noise prediction technology with emphasis on two current method for time domain calculations”, Journal of Sound and Vibration, 71(3), pp. 399-419, 1980