探索表面波驅動之聲射流現象

表面聲波在固-液界面上的傳播雖然已經被發現也被研究了很長的一段時間，但由於其應用範圍廣泛，結合不同的材料與設備更增加其利用價值與方向，從表面波被發展的地震領域到目前非常熱門的生物醫學領域，表面聲波都表現了它具有利用價值的一面，故仍舊有許多不同領域的學者投入其相關研究。而表面聲波學的理論也因其應用面的擴展，不斷的爲它投入新的元素，發展出結合其他理論的研究。本研究即是觀察利用壓電材料的壓電特性產生表面聲波以驅動聲射流的現象，是以結合壓電材料與表面聲波的相關研究，並增加理論推導的敘述及計算，以與實驗互相比較。本研究實驗採用4吋127.86°Y-X cut鈮酸鋰（LiNbO3）壓電材料以脈衝產生器頻率為10MHz驅動製作之交指叉轉能器，將水槽架設在交指叉轉能器與壓電材料上方觀察表面聲波驅動聲射流現象，並使用CCD攝影機將流場變化情況紀錄下來，再利用PIV分析軟體分析處理影像，得到流場速度圖以及數值，將這些數值整理得到流場中聲射流位置上之速度-時間圖。實驗與理論結果互相應證，本研究製作之交指叉電極以及觀察流場方式等實驗過程非常成功。

關鍵字

雷利波；聲射流；馬赫角；交指叉轉能器；壓電表面聲波；粒子影像測速技術

並列摘要

Propagation of SAW（surface acoustic waves）on a solid-liquid interface has been known and studied for a long time because of its broad varieties of applications. The SAW phenomenon was found by Rayleigh from studies in surface wave propagation of earthquake in 1885. Since then, the SAW has been studied in many different research areas. In this dissertation, we investigate the phenomenon of acoustic streaming driven by a SAW device. The device is made on 4-inches 127.86°Y-X cut LiNbO3 piezoelectric wafer. An IDT is patterned on the surface of the wafer to excite the Rayleigh waves. The device is driven by a sine-wave generator at 9.7MHz. A liquid container filled with water at a depth of 14cm is constructed on the wafer. When the device is driven at the aforementioned condition, acoustic streaming is observed. The flow field is recorded by a CCD camera and analyzed with PIV techniques. Velocity fields are measured. Velocity-time figures at 5 different observation positions in the fluid field are plotted. Directivity of the streaming jet agrees well with the theoretical prediction.

並列關鍵字

Rayleigh wave ； acoustic streaming jet ； Mach angle ； IDT ； piezoelectric SAW ； PIV

參考文獻

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探索表面波驅動之聲射流現象

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