振動圓柱對加熱凸塊之熱流分析

Abstract

本研究利用實驗方法分析管道內裝置往復運動的圓柱之後，對凸塊壁面附近速度以及溫度場的影響，且進一步探討凸塊壁面熱傳的增益。數值方面，利用流體力學計算軟體模擬實際情形，驗證實驗裝置的正確性。實驗方面，主要探討當振動圓柱在不同的振幅、振動頻率、雷諾數狀態下，對管道內凸塊壁面的熱傳效率影響。 由研究結果得知，在流場中圓柱進行往復式的振盪運動，受到圓柱牽引的效應，使管道內的流體呈現上下振盪的現象，引導流體向壁面衝擊，擾亂在圓柱後方壁面的流場，為提高熱傳效率的主要機制。此外，當圓柱振動的頻率接近流場的自然振動頻率時，會與管道內的流體產生共振的現象，此現象能夠大幅的增加流體的擾動，並且擾亂管道內的流場以及溫度場，產生較佳的熱傳增益。

The study investigates the heat transfer enhancement by a reciprocated oscillating cylinder in a channel flow. The characteristics of flow and thermal fields are analyzed experimentally. In the numerical analysis, computational fluid dynamics software is adopted to solve the flow and thermal fields. In the experimental investigation, the effects of Reynolds number, oscillating amplitude and oscillating frequency on the heat transfer characteristics of a heated block in the channel are examined. The results show that the oscillating cylinder induces the flow vibration. 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 oscillating frequency of the cylinder approach the natural vortex shedding frequency, because of the phenomenon of resonance in the channel flow, and the heat transfer rate is enhanced more remarkably.