Please use this identifier to cite or link to this item: `http://hdl.handle.net/11455/2718`
 標題: 振盪平板流場之數值模擬Numerical simulation of flow over an oscillating plate 作者: 許永璋Xu, Yong-Zhang 關鍵字: MECHANICAL-ENGINEERING;振盪平板流場;ENGINEERING;Discrete vortex method;Oscillating flat plate;Kutta condition;數值模擬;機械工程;工程;離散渦元法;振盪平板;庫達條件 出版社: 機械工程研究所 摘要: 本研究主要之目的在於使用離散元法來探討一均勻流流經一振盪之平板時 所造成之流場。在初始時，平板垂直於均勻流，而後在60 .degree.至 120 .degree. 範圍內作來回振盪。在不同之迴轉角速度下觀察流場中總 體性質與細部特性與固定平板流場之差異。以往的文獻中，由於缺乏振盪 平板之實驗數據及數值結果，本研究以定垂直平板流場的結果作為結果之 比較基礎。由本研究所得之結果可以發現，在振盪平板後之尾流之大型漩 渦會隨擺動角度上揚或下垂。在流場之 質方面，阻力係數、昇力係數及 史超赫數其值之變化皆大於固定垂直平板之流場所量測之結果。然而，渦 度脫落率及剪力層速度其值之變化卻略於固定垂直平板之流場所量測之結 果。其間之差異乃由於平板振盪影響所此外，在流場之細部特性方面，如 平均速度、均方根擾動速度及雷諾應力等，皆在平板後之尾流區取幾個不 同斷面作計算。一般而言，本研究所得結果與固定垂直平板之尾流流場之 特性有一致之趨勢。The flow filed of flow over an oscillating plate was numerically in the present study. The discrete vortex method wasmployed to carry out the numerical study. The flat plate was initiallyrmal to free stream and then oscillated between 60 .degree. and 120gree. with various angular velocities. Both the global and detailres of the oscillating plate flow field are examined. Due to lack ofrimental and numerical data available from previous investigations,thelts of the flow over a fixed normal flat plate were served as an basis in the present study. From the simulated results,it was foundthe wake behind the oscillated plate can be sweeping up or sweeping downcording to the status of rotation. The vorticity shedding frequency, ie,he Strouhal number,averaged drag and lift coefficients,shear layerelocities and rate of vorticty shedding were also computed.Generally, thetrouhal number,drag, and lift coefficients were found to be larger thanose of fixed normal flat plate flow field, while the shear layeres and rate of vorticity shedding were found to have smaller valuesaring with those of fixed normal flat plate case. These differencesprimarily due to rotation effects.Besides the above mentioned globals of flow field behind the oscillating plate , the detail features in thear wake region behind the oscillated plate were also investigated. Therage velocity , turbulence intensities, and Reynolds stress wereed at several locations in the down stream of wake. In general , thends of variations of these quantities were similar to those of fixedal plate except that rotation clearly enhence these profiles. URI: http://hdl.handle.net/11455/2718 Appears in Collections: 機械工程學系所