臺灣博碩士論文加值系統

本研究主要在利用數值模擬來探討均勻橫流中二維對稱雙射流受橫流作用產生流場的變化、干涉和發展。數值模擬主要以控制體積法配合 紊流模式，來模擬二維對稱雙射流在不同速度比R (射流流速/均勻橫流流速,R=9.33﹑5.67) 及不同偏角 (0度﹑9度﹑18度及27度)情形下，受橫流作用流場產生的變化、干涉及其發展情形。數值模擬以速度比R=9.33，射口偏角0°為邊界設定條件,並與實驗量測相驗證。結果顯示分佈趨勢相似。對於不同角度之數值模擬與實驗結果比較中其流場形貌、射流軌跡、平均流特性、紊流正應力與紊流剪應力皆發現有相似的分佈趨勢。在雙射流收斂域中，有不同強度的大小渦流群存在，同時於雙射流合流域的下游處，則有明顯的迴流域產生，且雙射流偏角改變時其迴流中心的位置並不隨射口偏角之不同而有明顯改變。而當R值改為5.67時比較各偏角下之流場流況發現其迴流中心並未固定在相同的位置﹐此現象與R=9.33時之結果比較差異較大。

This paper presents a numerical study of the problem of symmetric planar dual parallel or inclined jets discharge into a confined uniform cross flow. Control volume method is used for simulating the mean quantities of the averaged Navier-Stokes equations associated with model for the turbulence closure. Two symmetric nozzles are settled with an angle of 0、9、18 and 27 degrees to establish a combined jet normal to the cross flow. The mean flow configuration, normal and shear stresses in the longitudinal The numerical results show a good agreement with the experimental measurements. Vortices are presented unsymmetrically in the converging region of the dual jets, and recirculation flow occurs between the downstream of combined jets and the solid boundary. Also the position of the center of recirculation in the combined region for different inclined angels is almost the same for R=9.33. When R=5.67 we cannot get the similar results for the position as that in R=9.33.