切型渦漩層流近場實驗研究

Laminar Swirling Pipe Flow: Near-Field Experiments

王安邦(An-Bang Wang) ； 施江林(Jiang-Lin Shih) ； 王宏杰(Homg-Jee Wang)

《中國航空太空學會學刊》 28卷2期 (1996/06) Pp. 91-98

https://doi.org/10.6124/TAASRC.199606_28(2).01

摘要

本文主要目的乃在定性與定量上去探討雙管切型渦漩層流在圓管中之流場，重點特別放在文獻中所最缺乏的近場流力結構分析。實驗之切向雷諾數範圖爲97至2,100。在渦漩層流場中，吾人利用流場顯影與LDA定量量測相互配合，發現流場之近場結構大致上可分爲三個不同特隘的區域：(1)上游中心圓錐區，(2)中心迴流區以及(3)外環區。外環區在渦漩近場基本上仍是三維之速度分佈，但在中心軸附近之流場結構則已大致呈現爲旋轉軸對稱。另外，吾人也發現：縱使在不同的切向雷諾數下，若選擇適當的無因次化特徵長度及特徵速度，流場結構於軸向及切向均具有相當程度之相似性。具此相似特性之無因次角速度其最大值均發生在迴流區之中心附近，且其在渦漩近場大致以每隔一個中心迴流區長度遞減爲原值1/10的速率減小。本文之量測數據與分析探討將有助於未來渦漩流計算模式的發展與模擬程式檢驗之基礎。

關鍵字

渦漩層流 ； 近場流場 ； 流場顯影 ； 雷射都卜勒測速儀

並列摘要

Main Purpose of this paper is to investigate the flow structure in the near field of a laminar swirling flow caused by injection of two tangential jets into a circular pipe. The flows was studied for the Reynolds number from 97 to 2,100. Based on results of flow-visualizations and the LDA-measurements, the flow structure of this study could be devided into three different characteristic zones. They are (a) upstream central zone, (b) central recirculation zone and (c) outer annular zone. Although the flow shows a three-dimensional velocity distributions in the outer annular zone in the near flow-field, however, it reveals a flow structure with nearly rotational symmetry in the central regions. By adequate choosing the characteristic velocity and length scales, the flow structure was found to have the character of similarity for different Reynolds numbers. This paper offers a useful data base for developing and testing of a numerical modelling of swirling flows in the future.

並列關鍵字

Laminar swirling flow ； near field ； flow-visualization ； LDA