本文研究水電式汽泡產生器在去離子水及塩水溶液中之特性。汽泡是透過水中電極之高壓放電而產生的，我們利用高速攝影機，將汽泡成長及收縮的過程拍攝下來，並利用電腦處理所拍攝到的影像，以量測汽泡之最大尺寸，找出放電電壓與汽泡尺寸間的關係。在此部份的實驗中，我們也對電極及其他可能影響汽泡尺寸重複性的因素做了一番探討。為了量測汽泡對鄰近固體表面所造成的衝擊力，我們將電極靠近水槽底部的平板，並在電極下方的平板上安置一PVDF (polyvinylidene fluoride) 壓電薄膜。為了避免量測電路的負載效應，我們先將PVDF壓電薄膜串接一個自製的運算放大器後，再接於數位示波器。除了衝擊力的大小之外，我們亦量測了衝擊訊號之持續時間，第一及第二次衝擊的時間差等數據。所有量測分別在導電度不同的兩種液體中進行，以比較兩者間的差異。本研究結果期望能有助於掌握水電式汽泡產生器之特性，提高其在醫學工程應用上 (如體外震波碎石機) 之穩定性。

Characteristics of a hydroelectrical bubble generator in deionized water and saline of concentration 100g/l have been studied experimentally. Vapor bubble was produced by means of high-voltage electrical discharge. Growth and collapse of the bubble were photographed using a high-speed camera and the images were employed to measure the maximum size of the bubble. Relationship between the discharge voltage and the size of bubble was determined. Influences of electrode gap and other possible factors on the reproducibility of the bubble size were also examined. In order to measure the impact force caused by the collapse of the bubble near a rigid boundary, the electrodes were placed close to the plate of the cuvette and a PVDF piezoelectric film was implemented. The output of the PVDF film was connected to a home-made operation amplifier to eliminate loading effects of the measurement system. The signal was then recorded by a digital oscilloscope. In addition to the magnitude of the impact force, time duration of the impact signal and the time interval, experimental results obtained in water with two different electrical conductivities were compared. It is hoped that the present study can help understand the characteristics of the hydroelectrical bubble generator and find applications in medical engineering, sush as the improvement of the reproducibility of the shock wave generator for extracorporeal lithotripsy.

Arndt, R. E. A., Ellis, C. R., and Paul, S., “Preliminary Investigation of the Use of Air Injection to Mitigate Cavitation Erosion”, ASME Journal of Fluids Engineering, 117, 498-504. (1995)

Arndt, R. E. A., Paul, S., and Ellis, C. R., “Application of Piezoelectric Film in Cavitation Research”, Journal of hydraulic engineering, 123, 539-548. (1997)

Bailitis, E., Der Schallimpuls eines Flüssigkeitsfunkens., “the Pressure Pulse of a Liquid Spark”, Zeitschrift für angewandte Physik einschlieâlch Nukleonik, Vol. 9, pp. 429-434. (1957)

Benjamin, T. B. & Ellis, A. T., “The collapse of cavitation bubbles and the pressures thereby produced against solid boundaries”, Phil. Trans. R. Soc. Lond. A. 260, 221-240. (1966)

Blake, J. R. & Gibson, D. C., “Cavitation bubbles near boundaries”, A. Rev. Fluid Mech. 19, 99-123. (1987)

Chaussy, C., Schmiedt, E., Jocham, D., Brendel, W., Forssmann, B., and Walther, W., “First Clinical Experience with Extracorporeally Induced Destruction of Kidney Stones by Shock Waves”, Journal of Urology, Vol. 127, pp. 417-420. (1982)

Chaussy, C., Schmiedt, E., Jocham, D., Schuller, J., Brendel, H., and Liedl, B., “Extracorporeal Shock-Wave Lithotripsy (ESWL) for Treatment of Urolithiasis”, Urology, Vol. 93, pp. 59. (1984)

D. Cathignol, J. L. Mestas, F. Gomez & P. Lenz., “Influence of water conductivity on the efficiency and the reproducibility of electrohydraulic shock wave generation”, Ultrasound in medicine & Biology, Vol. 17, No. 8, 819-828. (1991)

Granz, B., Holzapfel, R., and Köhler, G., “Meausrement of shock waves in the focus of a lithotripter”, IEEE Ultrasonic symposium, 991-994. (1989)

Harrison, M. “An enpenmental study of single bubble cavitation noise”, J. Acoust. Soc. Am. 24, 77~782. (1952)

Häusler, E. and Kiefer, W., “Anregung von Stosswellen in Flüssigkeiten durch Hochgeschwindigkeitswassertropfen”, Verh Dtsch Physik Ges, Vol. 10, pp. 36. (1971)

Jones, I. R. & Edwards, D. H., “An experimental study of the forces generated by the collapse of transient cavities in water”, J. Fluid Mech. 7, 596-609. (1960)

Kazuyoshi Takayama, Osamu Onadera, Tetsuro Obara, Masaaki Kuwahara, & Osamu Kitayama., “Underwater shock wave focusing by microexplosions, a medical application”, 日本機械學會論文集, Vol. 57, No. 539. (1991)

Kornfeld, M. & Suvorov, L., “On the destructive action of cavitation”, J. Appl. Phys. 15, 409-425. (1944)

Lauterborn, W. “Cavitation bubble dynamics - new tools for an intricate problem”, Appl. Sci. Res. 38, 165-178. (1982)

Momma, T., and Lichtarowicz, A., “A Study of Pressure and Erosion Produced by Collapsing Cavitation”, Wear, 186-187, 425-436. (1995)

Naude’, C. F. & Ellis, A. T. “On the mechanism of cavitation damage by nonhemispherical cavities collapsing in contact with a solid boundary”, Trans. ASME D: J. Basic Eng, 83. 648-656. (1961)

Okada, T., Iwai, Y., and Awazu, K., "A Study of Cavitation Bubble Collapse pressure and Erosion Part 1: A Method for Measurement of Collapse Pressure”, Wear, 133, 219-232. (1989)

Okada, T., Iwai, Y., Ishimaru, H., and Maekawa, N., “Measurement and Evaluation of Cavitation Bubble Collapse Pressures”, JSME International Journal Series A, 37, 37-42. (1994)

P. Broyer, D. Cathignol, Y. Theillere, J. L. Mestas., “High-efficiency shock-wave generator for extracorporeal lithotripsy”, Med. & Biol. Eng. & Comput., Vol. 34, 321-328. (1996)

Patrick, T., Hunter, Birdwell Finlayson, Robert, J., Hirko, Wallace, C., Voreck,Raymond Walker, Scott Walck, Mohammed Nasr, “Measurement of Shock WavePressures Used for Lithotripsy”, Journal of Urology, Vol. 136, pp. 733-738. (1986)

Pavel Sunka, “Pulse electrical discharges in water and their applications”, Physics of plasmas, Vol. 8, No. 5, 2587-2594. (2001)

Rayleigh, Lord, “On the pressure developed during the collapse of a spherical cavity”, Phil. Mag. 34, 94-98. (1917)

Schiffers, W. P., Shaw, S. J. ,Emmony, D.C., “Acoustical and optical tracking of the collapse of a laser-generated cavitation bubble near a solid boundary”, Ultrasonics, 36 , 559-563.(1998)

Shaw, S. J., Schiffers, W. P., Gentry, T. P., and Emmony, D. C., “ The interaction of a laser-generated cavity with a solid boundary”, J. Acoust. Soc. Am., 107(6), 3065-3072. (2000)

Shenqyang S. Shy, “Analysis of shock waves in liquids：A study of noninvasive fracturing of kidney stones”, Journal of the Chinese Society of Mechanical Engineers, Vol. 16, No. 6, 621-628. (1995)

Shima, A., Takayama, K., Tomita, Y.& Miura, N. “An experimental study on effects of a solid wall on the motion of bubbles and shock waves in bubble collapse”, Acustica 48, 293-301. (1981)

Shima, A., Takayama, K., Tomita, Y. & Ohsawa, N., “Mechanism of impact pressure generation from spark-generated bubble collapse near a wall”, AIAA J. 21, 55-59. (1983)

Shutler, N. D. & Mesler, R. B., “A photographic study of the dynamics and damage capabilities of bubbles collapsing near solid boundaries”, Trans. ASME D: J. Basic Engng 87, 511-517. (1965)

Soyama,H., Lichtarowicz, A., Momma, T., and Williams, E.J., “A new calibration method for dynamically loaded transducers and its application to cavitation impact measurement”, ASME Journal of Fluids Engineering., 120, 712-718. (1998)

T. C. K. Molyneaux, Long-Yuan Li & N. Firth., “Numerical simulation of underwater explosions”, Computers Fluids, Vol. 23, No. 7, 903-911. (1994)

Teslenko V.S., Zhukov A.I., Mitrofanov V.V., Drozhin A.P., “A multispark electric discharge in a liquid”, IEEE, 275-278. (1997)

Tomita, Y. & Shima, A., “Mechanisms of impulsive pressure generation and damage pit formation by bubble collapse”, J. Fluid Mech. 169, 535-564. (1986)

Tong, R. P., Schiffers, W. P., Shaw, S. J., Blake, J. R. and Emmony, D. C., “The role of ‘splashing’ in the collapse of a laser-generated cavity near arigid boundary”, J. Fluid Mech. , 380, 339-361. (1999)

Vogel, A. & Lauterborn, W., “Acoustic transient generation by laser-produced cavitation bubbles near solid boundaries”, J. Acoust. Soc. Am. 84, 719-731. (1988)

Vogel, A., Lauterborn, W. & Timm, R., “Optical and acoustic investigations of the dynamics of laser-produced cavitation bubbles near a solid boundary”, J. Fluid Mech. 206, 299-338. (1989)

周明忠, “水下爆炸汽泡動力行為及壓力場之研究”, 國立成功大學造船暨船舶機械工程研究所碩士論文, 1999.

陳郁文, “利用壓電薄膜量測空蝕汽泡對鄰近物體表面所造成之衝擊力”,國立成功大學機械工程研究所碩士論文, 2001.

顏志成, “水電型體外震波碎機電極之間距控制設計”, 國立成功大學航空太空工程研究所碩士論文, 2001.