Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/1974
標題: 三維紊流雙噴射撞擊流場數值模擬與分析
Numerical Simulation and Analysis of Three-Dimensional Turbulent Impinging Twin-Jet Flowfield
作者: 聶祖蕊
Nieh, Tsu-Jui
關鍵字: impingement
三維紊流
three-dimensional
circulating flow
twin-jet
wall jets
upwash
橫向流
雙噴射撞擊流場
上沖噴泉流
迴流
出版社: 機械工程學系
摘要: 此次研究使用套裝軟體PHOENICS進行數值運算, 對三維紊流雙噴射撞擊流 作綜合性的探討.噴射撞擊流在應用上大都具有極強的紊流特性, 此次研 究採用k-e雙方程式紊流模式, 並以控制體積積分法建立有限差分方程式. 按SIMPLEST計算程序求解, 以模擬三維, 恆溫, 不 可壓縮之矩形雙噴射 撞擊流場. 分別就橫向流的有無, 兩噴口中心間距, 噴嘴角度及噴流 速 度等參數變化對流場中速度, 壓力, 及結構的影響逐一討論. 兩噴射主流撞擊下平板面後將產生上沖噴泉流, 流體間交互作用又將產生 數個迴流, 各參 數的改變對流場結構影響非常大, 進而對上平板面的壓 力也有很大的影響. 若應用在垂直 /短程起降 (V/STOL) 飛機起降時的流 場情況, 則對飛機本身的升力與控制將造成或好或壞的影響. 整體而言, 橫向流使下平板面的壁合流區及停滯線呈彎曲狀, 也使上沖噴 泉流偏向, 造成 對稱流場不再對稱. 當噴射主流偏向角度太大, 則不會 有噴泉流的產生. 各參數的變化也 都會影響上沖噴泉流的強度與迴流的 大小, 數目及位置.
There have been a lot of researches investigated the jet impingement problem by using experiment or numerical simulation. But none of them investigated the phenomena of the three- dimensional turbulent impinging twin-jet flowfield. In this study, a computational fluid dynamics (CFD) code, PHOENICS, is used to calculate the properties on the three-dimensional turbulent impinging twin-jet flowfield. The impinging flowfield is strongly three dimensional, as well as turbulent. The k-e two-equation turbulence model and the control-volume integration formulafor finite difference and SIMPLEST algorithm are employed to simulate the three- dimensional, isothermal, incompressible flowfield. The effect of the crossflow velocity, the nozzle-to-nozzle centerline spacing, the nozzle-to-impingement surface spacing, the impinging angles and the jet-inlet velocity on the flowfield structure will be studied one by one. The jets impinge upon the lower plate and create lower wall jets. Some of the wall jets collide with each other and turn upward to form an upwash fountain which increases the lift force of the upper plate. The fluid surrounding the jets is entrained at the boundaries of the jets which results an induced circulating flow. At some situation, this secondary flow causes the upper plate to have a suck-down force phenomenon.
URI: http://hdl.handle.net/11455/1974
Appears in Collections:機械工程學系所

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