Noise generation From an Airfoil in Non-uniform flows

• Main Authors: Wen-Chu Lai, 賴文舉
• Other Authors: San-Yin Lin
• Format: Others
• Language: zh-TW
• Published: 1999
• Online Access: http://ndltd.ncl.edu.tw/handle/57379600467913269620

碩士 === 國立成功大學 === 航空太空工程學系 === 87 === The major purpose of this thesis is to numerically study noise generated through non-uniform flow past a body. The flat plate and Joukowski airfoil are selected as our physical models. The flow fields and pressure fluctuation by gust past these two physical models are simulated. Furthermore, the effects of different gust reduced frequencies, gust amplitudes and gust types are investigated. In the whole problem, we adapt a numerical method to solve the two-dimensional compressible Euler equation. A fifth-order Weighted Essentially Non-Oscillatory method and a four-stage Runge-Kutta time integration method are used here. In the gust/plate problem, when at low frequency, the effect of gust amplitude is linear. Most of the noise comes from the leading edge. When at high frequency, the effect of gust amplitude has noticeable nonlinear effect. The numerical results radiate that there is considerably less noise radiated than at the lower frequency. In the gust/airfoil problem, the noise phenomenon are very similar to results in the gust/plate problem.