橫向振動加熱圓柱在渠道內流場與熱傳特性之數值模擬

Numerical Simulation of Flow and Heat Transfer Characteristics in the Channel with a Transversely Oscillating Heated Circular Cylinder

王忠義(Chung-Yi Wang)

指導教授 ： 顏瑞和

國立臺灣大學/工學院/機械工程學研究所/碩士(2008年)

https://doi.org/10.6342/NTU.2008.01335

摘要

本研究利用數值方法探討渠道內橫向振動加熱圓柱對流場與熱傳特性影響，數值方面是採用ALE 運動描述法來處理流體與固體介面相互影響的問題，並使用寬頻元素法配合非結構性網格加以分析。首先針對不同的振動振幅、振動頻率、雷諾數和阻塞比參數，分析渠道內橫向振動圓柱對尾流場渦漩形態的影響；進而探討渠道內橫向振動加熱圓柱的熱傳特性。
由研究結果得知，圓柱尾流場的渦漩形態，會受到振動頻率和振幅的影響，產生不同的渦漩形態，而阻塞比會使流場渦漩形態的轉變延遲發生；在圓柱熱傳效率部份，高振幅和高阻塞比的條件會讓渠道內流場的鎖頻區範圍增加，當渠道內流場發生鎖頻現象時，能夠有效增加流體的擾動，提升圓柱的熱傳效率。

關鍵字

寬頻元素法 ； ALE 運動描述法 ； 非結構性網格 ； 管道流 ； 振動圓柱 ； 阻塞比

並列摘要

The study investigates the flow and heat transfer characteristics in the channel with a transversely oscillating heated circular cylinder. The variations of flow and thermal fields are classified into a class of moving boundary problems. In the numerical analysis, a spectral element formulation with arbitrary Langrangian-Eulerian method is adopted to solve the flow and thermal fields for moving boundary problem. The subsequent developments of the vortex shedding and heat transfer characteristics around the heat cylinders are presented in detail. The effect of Reynolds number, oscillating amplitude, oscillating frequency, blockage ratio on the flow structures and heat transfer characteristics of the heated cylinder are examined. The results show that the interaction between the oscillating cylinder and vortex shedding from the cylinder dominates the state of the wake. This phenomenon would disturb the flow and thermal fields in the channel flow and the heat transfer rate in the channel would be enhanced. Furthermore, as the flow and thermal fields may approach a periodic state in lock-in regime. The heat transfer of the cylinder in the lock-in regine is enhanced remarkably.

並列關鍵字

Spectral element, ； ALE method ； Unstructured element ； Oscillating cylinder ； Channel flow ； Blockage ratio

參考文獻

35.黃坤, 非結構性寬頻元素法於二維/三維不可壓縮層流流場之發展與應用, 國立臺灣大學機械工程學研究所, 碩士論文 2007.

36.簡志偉, 非結構性寬頻元素法應用於二維不可壓縮流場之研究, 國立臺灣大學機械工程學研究所, 碩士論文 2006.

45.洪立昕, 寬頻元素法應用於解非結構性元素Helmholtz方程式, 國立臺灣大學機械工程學研究所, 碩士論文 2005.

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