本研究旨在探討氣泡誘導聲流效應在不同寬高比(AR)微流道中的流場現象、熱傳特性及其間之關係。利用微粒子影像測速法並搭配流場可視化技術與溫度螢光感測塗料之量測技術對氣泡誘導聲流效應進行流場量測以及熱傳分析。矩形直管微流道之材質為聚二甲基矽氧烷(PDMS)，其AR分別為3.125、2.5與1.875，在流道的兩側設計交錯式的凹槽結構以利形成氣泡，並在凹槽出口處安置一微小的障礙物幫助維持氣泡形狀。氣泡誘導聲流效應乃利用開啟壓電片來擾動流場，所探討之雷諾數(Re)分別為2、4、6及8。流場實驗結果發現氣泡誘導聲流效應在不同AR的流道，於四個Re時皆可影響至流場中心(y/W=0)；同一流道在Re為2、4、6、8時的氣泡誘導聲效應隨著主流速度越快而逐漸變得不明顯，且Re的提高造成氣泡被抑制；在流場中心(y/W=0)與Re =2、4時，AR=2.5流道的氣泡誘導聲流效應影響最劇烈，其最大的垂直速度分量(V)的變化ΔV*在Re=2、4分別為2.03與0.95，而在Re=6、8時，AR=1.875流道的氣泡誘導聲流效應影響最劇烈，其最大的ΔV*在Re=6、8分別為0.49與0.65。進行熱傳實驗時，熱邊界條件為以定熱通量(0.2 W/mm2)方式於流道底部加熱，量測不同AR流道在Re=2、4、6時關閉與開啟壓電片的液體溫度及壁面溫度，並計算入出口焓值變化與紐索數(Nu)變化。熱傳實驗結果發現在AR=2.5與Re=4時，氣泡誘導聲流效應最為明顯；其關閉與開啟壓電片的焓值增益達43.77%，而於流道中心位置(y/W=0)最大的Nu增益約101.5%。藉由焓值增益與ΔV*觀察熱傳與流場之間的關係，發現在Re=2、4時，焓值增益與ΔV*隨AR增加先上升再下降，在AR=2.5有最大焓值增益，而其對應的流場也有最大的ΔV*；在Re=6時，焓值增益與ΔV*隨AR增加單調下降，在AR=1.875有最大焓值增益，而其對應的流場也有最大的ΔV*。

This study aims to investigate the bubble-induced acoustic streaming effect on microchannel flow, heat transfer analysis and the relation in different aspect ratio (AR, channel width/high). The flow field and heat transfer analysis with bubble-induced acoustic streaming were analyzed by using the flow visualization (FV) technique, Micro Particle Image Velocimetry (µ-PIV) and Temperature-Sensitive Paint (TSP) technique. Different AR(=3.125, 2.5, 1.875) rectangular microchannels with multiple staggered cavities with baffle were fabricated with PDMS as the material by soft lithography. The cavities with baffle were positioned at the sidewall of the microchannel, and the design of the baffle at the exit of cavity is to maintain the shape of bubble. The bubble-induced acoustic streaming was driven by a piezoelectric (PZT) powered by a power supply and Reynolds number(Re) 2, 4, 6, 8 were measured. From the experimental result, the velocity profiles were affected at the center of microchannel(y/W=0) at different AR microchannels and Re with bubble-induced acoustic streaming. At same microchannel, the bubble-induced acoustic streaming and bubbles were suppressed with the increase of Re. At the center of microchannel(y/W=0) and Re=2, 4, the bubble-induced acoustic streaming could provide most effective disturbance at the AR=2.5 microchannel, and the biggest change of velocity V component (ΔV*) were 2.033 and 0.951. At y/W=0 and Re=6, 8, the bubble-induced acoustic streaming could provide most effective disturbance at the AR=1.875 microchannel, and the biggest ΔV* were 0.486 and 0.653. Using different AR to measure the temperature field. Liquid temperature, wall temperature, the change of enthalpy and Nusselt number at close and open PZT and Re=2, 4, 6 with constant heat flux of 0.2 W/mm2 boudnary condition at the bottom of microchannel. The bubble-induced acoustic streaming could provide most effective disturbance at AR=2.5 microchannel and Re=4, the highest enthalpy change between microchannel inlet and exit could reach about 43.77%, and at center of microchannel(y/W=0), the highest heat transfer enhancement would reach about 101.5%. Using enthalpy enhancement and ΔV* to observe the relation of heat transfer and microchannel flow. At Re=2, 4, enthalpy enhancement and ΔV* increased first and then decreased when AR increased; At Re=6, enthalpy enhancement and ΔV* monotonically decreased when AR increased.

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