噴射衝擊水平旋轉圓柱之熱流分析

Three-dimensional Laminar Convective Flows around a Rotating Horizontal Cylinder with an Incident Hot Jet

鄭世昌(Shih-Chang Cheng)

指導教授 ： 林育才

元智大學/工程學院/機械工程學系/碩士(1998年)

摘要

本篇論文主要是針對高溫流體經由噴嘴噴射衝擊至水平旋轉圓柱之後所產生的現象作熱流分析。其中共分為兩個部分，當工作流體是低溫時（400K）考慮強制對流；當工作流體是高溫時（2000K）考慮混合對流。事實上，在高溫的情況中，因為自然對流與強制對流結合之後所產生的速度會使得旋轉的效應變的非常不明顯。而文中也指出了圓柱上的熱傳遞現象會受到噴嘴速度與噴嘴大小的影響。不過，這樣的影響並不是一直無限增加二會有一個臨界的值存在。

關鍵字

噴射衝擊 ； 水平旋轉圓柱 ； 傳導

並列摘要

Convective flows on a rotating horizontal cylinder with an hot incident jet are numerically investigated in the present study. The study is related to the outside vapor deposition (OVD) process for manufacturing optical fiber preforms. The results show that the temperature of the cylinder is affected by the incident jet temperature, the jet velocity and the jet width. When the jet temperature is close to the ambient temperature, the buoyancy effect can be ignored and the resulting temperature and velocity field of the gas is symmetrical. At low rotational speed of the cylinder, the effect of rotation can be neglected for the cases studied. When the Reynolds increases the pattern of the flow field changes and a recirculation zone may form. The highest temperature on the cylinder increases with the jet velocity. As the jet temperature increases, the flow pattern is different due to the buoyancy effect and the maximum velocity occurs at the location above the cylinder. For small Reynolds numbers, the flow approaches to the +y axis for larger buoyancy effect. As the Reynolds number increases, the buoyancy effect decreases and the flow approaches to the x axis. It is also found that the temperature on the cylinder increases as the jet width increases. However, there exists a critical limit for the cylinder temperature for further increase of the jet width.

並列關鍵字

incident hot jet ； rotating horizontal cylinder ； conduction

參考文獻

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