本研究以田口式L18表實驗方法，探討液態金屬在具漩渦內混式霧化器之噴嘴幾何參數控制因子與實驗操作參數控制因子之最佳設計，研究目標以所產生之金屬粉末中V（10-20）體積百分比最大值為之設計條件。本研究所探討的噴嘴幾何參數控制因子包括：噴嘴出口管道長度、液體流道孔徑、氣體流道偏置量、噴嘴出口孔徑面積。實驗操作參數控制因子包括：霧化氣體壓力、冷卻氣體壓力、氣液壓差比（2△P/△Pmax）、加熱爐溫度。實驗結果顯示，最佳設計組合為噴嘴出口管道長度為0.5mm、液體流道孔徑為ψ1.5mm、氣體流道偏置量為6mm、噴嘴出口孔徑面積為24mm2、霧化氣體壓力為5kg/cm2、冷卻氣體量為1kg/cm2、氣液壓差比（2△P/△Pmax）為2和加熱爐溫度為300℃，在此最佳設計條件之實驗結果金屬粒徑分佈在10 到20μm之間的體積百分比高達79.51﹪。

　　研究結果亦顯示：（1）噴嘴出口管道長度愈短，流體在流道中之摩擦損失愈小，故其漩渦強度較大，可以在噴口形成較強之薄膜化霧化機制，故其霧化效果較佳。（2）液體流道孔徑變小時，液態金屬束愈細，則氣體的衝擊能量愈能夠有效地造成液態金屬之霧化，故可得較細之成金屬粉末。（3）當漩渦產生時，因為流體漩渦動量之流通量與氣體流道偏置量之平方成正比，而流體軸向動量之流通量氣體流道偏置量成正比，故氣體流道偏置量愈大，漩渦數S愈高，其薄膜化之霧化機制愈顯著。（4）噴嘴出口孔徑面積達某一數值時，霧化特性不會有進一步之改善。這是因為當噴嘴出口孔徑面積變大時，霧化氣體之流量變大可傳達於液態金屬之霧化能量增加，故可產生較細之成金屬粉末。但當噴嘴出口孔徑面積大到某一值時，衝擊氣體能量轉換效率變低，故未能將進一步增進霧化效果。（5）霧化氣體壓力增加，則衝擊能量會愈大，故造成較佳之霧化效果。（6）施加冷卻氣體時，因為冷卻氣體的溫度為常溫，故可對液態金屬噴霧進一步造成冷卻凝固之效果，使得粒子在碰撞後不會黏在一起，故可得較細之金屬粉末。（7）氣液壓差比愈大時，液體壓力愈小，故金屬流量愈小，則液態金屬束愈細，則氣體的衝擊能量愈能夠有效地對液態金屬造成霧化作用，故可得較細之金屬粉末。（8）加熱爐溫度愈高，液態金屬在較高的溫度下，黏滯係數μ（Viscosity）與表面張力σ（Surface Tension）降低，有利於液態金屬之霧化，得到更小的金屬粉末。

　　Taguchi experimental method is used to investigate the optimum conditions to produce solder powder in the size range of 10μm to 20μm. The eutectic metal is first heat up in the crucible to the metal temperature. The melt is then delivered to the atomizer and is injected to the cooling chamber. A swirl type internal-mixing atomizer is employed to produce the metal powder. The design parameters of the atomizer and the operational parameters are used to characterize the atomizer. The design parameters include the length of the atomizer outlet channel 、 the diameter of melt tube 、 the offset of the gas inlet and the area of the atomizer outlet orifice. The operational parameters include the cooling gas pressure 、 the atomization pressure of the gas、 the pressure ratio between the gas and the melt（2△P/△Pmax） and the heating temperature. Results show that the optimum conditions are ： the length of the atomizer outlet channel=0.5mm 、 the diameter of melt tube=1.5mm 、 the offset of the gas inlet=6mm 、 the area of the atomizer outlet orifice=24mm2 、 the cooling gas pressure=1kg/cm2 、 the atomization pressure=5kg/cm2 、 the pressure ratio=2 and the heating temperature=300℃. Under this optimum conditions, we can obtain a yield rate of 79.51﹪of the powders with size between 10μm to 20μm.

　　Results also show that ：（1）We can achieve better performance by reducing the atomizer outlet length because of the reduction in pressure loss. （2）By reducing the diameter of the melt tube, the atomization efficiency is improved. （3）The increase of offset of the gas inlet results in a higher swirling effect on the atomization medium. Hence a prefilming effect occurs and we can obtain the better atomization performance. （4）The area of the atomizer orifice reach an optimum condition when the flow reaches the choking condition at a higher gas-to-melt mass ratio. （5）Higher atomization pressure favors the atomization processes. （6）We achieve better performance by applying the cooling gas at the outlet of the atomizer. The cooling processes enhance the solidification of the spray droplets and eliminate the agglomeration of the droplets. （7）The increase of the pressure ratio between the gas and melt results in a reduction of the melt pressure and a higher gas-to-melt ratio. Hence we can achieve better performance by raising the pressure ratio.（8）The increase in heating temperature results in the reduction of the viscosity and surface tension of the melt. Hence we achieve better atomization performance by increasing the heating temperature.

[1] Lefebvre, A. H., ”Atomization and Spary,” Hemisphere Publishing
Corporation, New York, pp.1-25 , 1989。

[2] 李輝煌，田口方法（Taguchi Methods）品質設計的原理與實務，高立圖書有限公司，2000。

[3] 田口玄一、吉澤正孝，田口式品質工程講座（一）開發設計階段的品質工程，中國生產力中心，1990。

[4] 田口玄一、山本昌吳，田口式品質工程講座 (二)製造階段的品質工程，中國生產力中心，1991。

[5] 田口玄一、小西省三，田口式品質工程講座(三)品質評價的S/N比，中國生產力中心，1991。

[6] 田口玄一、橫山巽子，田口式品質工程講座(四) 品質設計的實驗計畫法，中國生產力中心，1995。

[7] 丁志華等，田口實驗計畫法簡介（I）奈米通訊，第八卷 第 三 期 2001。

[8] Castleman, R. A., Jr., “The Mechanism of the Atomization of Liquids,”Burean of Standards Journal of Research, Vol. 6, pp. 369-376, 1930。

[9] Lefebvre, A. H., “Gas Turbine Combustion,” Chapter 10, Hemisphere Publishing Corporation, New York, 1983.

[10] Dombrowski, N. and Johns, W. R., “The Aerodynamic Instability and Disintegration of Viscous Liquid Sheets,” Chem. Eng. Sci., Vol. 18, pp. 203-214, 1963.

[11] Stapper, B. E., Sowa, W. A. and Samuelsen, G. S., ”An Experimental Study of the Effects of Liquid Properties on the Breakup of a Two-dimensional Liquid Sheet,” ASME, Journal of Engineering for Gas Turbines and Power, Vol. 114, pp. 39-45, 1992.

[12] Fraser, R. P., ”Liquid Fuel Atomization, ” Sixth Symposium(International) on Combustion, Rein-hold, New York, pp.687-701,1957.

[13] Simmons, H. C., “The Atomization of Liquid, Principles and Methods,” Parker Hannifin Report, No.7901/2-0, 1979.

[14] Cubberly, and William, H. Metal Handbook. ninth ed., Vol. 7, Powder Metallurgy, American Society for Metal, 1984.

[15] Tallmadge, J. A., “Powder Production by Gas and Water Atomization of Liquid Metals,” Powder Metallurgy Processing, Kuhn, H. S. and Lawley, A. (eds.), Academic Press, New York, NY, pp. 1-32, 1978.

[16] Tamura, K. and Takeda, T., “Production of Copper Powder by Atomization,” Trans. Nat. Res. Inst. Metals (Japan), vol. 5,pp. 252-256, 1963.

[17] German A. and Randall, M., Powder Metallurgy Science. Metal Powder Industries Federation, Princeton, N.J., 1994.

[18] Nukiyama, S. and Tanasawa, Y., "Experiments on Atomization of Liquids in an Airstream," Transaction of JSME, Vol. 5, No. 18, pp. 68-75, 1939.

[19] Gretzinger, J. and Marshall, W.R. Jr., "Characteristics of Pneumatic Atomization," AIChE Journal, Vol. 7, No. 2, pp. 312-318, Jun. 1961.

[20] Kim, K.Y., and Marshall, W.R. Jr., "Drop-Size Distributions from Pneumatic Atomizers," AIChE Journal, Vol. 17, No. 3, pp. 575-584, May 1971.

[21] Tate, R.W., "Droplet Size Distribution Data for Internal-Mixing Pneumatic Atomizers," Proceeding of the 3rd ICLASS," pp. IIC/1/1-13, 1985.

[22] Rizkalla, A. A. and Lefebvre A.H., "Influence of Liquid Properties on Airblast Atomizer Spray Characteristics,” J. Eng. Power, pp. 173-179, April 1975.

[23] Rizkalla, A. A. and Lefebvre A.H., “The Influence of Air and Liquid Properties on Airblast Atomization,” J. Fluids Eng., Vol. 97, pp. 316-320, 1975

[24] Rizk, N. K. and Lefebvre, A. H., ”Influence of Atomizer DesignFeature on Mean Drop Size,” AIAA Journal, Vol. 21, No. 8, pp.1139-1142, 1983.

[25] Beck, J., Lefebvre, A. H. and Koblish, T., ”Air Blast Atomization at Conditions of Low Air Velocity,” Paper No AIAA- 89-0217, 1989.

[26] Beck, J. E., Lefebvre A. H. and Koblish, T. R., “Liquid Sheet Disintegration by Impinging Air Streams,”Atomization and Sprays, Vol. 1, No. 2, pp. 155-170, 1991.

[27] Beck, J. E. and Lefebvre A. H., "Airblast Atomization at Conditions of Low Air Velocity," J. Propulsion, Vol. 7, NO.2, March-April, 1991.

[28] Aligner, M. and Wittig, S., "Swirl and Counter Swirl Effects in Prefilming Airblast Atomization", Trans. ASME, J. Eng. Power, Vol. 102, pp.706-710, 1980.

[29] 許耀仁，氣衝式平面噴嘴液膜霧化特性之研究，國立成功大學航太所碩士論文，1993。

[30] Sattelmayer, T. and Witting, S., ”Internal Flow Effects in Prefilming Airblast Atomizers Mechanisms of Atomization and Droplet Spectra,” ASME Journal of Engineering for Gas Turbine and Power, Vol. 108, pp.465-472, 1986.

[31] Rizk, N.K. and Lefebvre, A.H., “Spray Characteristics of Plain-jet Airblast Atomizer,” Transaction of The ASME vol. 106, July 1984.

[32] Press, C., Gupta, A.K. and Semerjian, H.G., "Aerodynamic Effects on Fuel Spray Characteristics: Air-assist Atomizer, "HTD-vol.104, pp.111-119, 1988.

[33] Kevin, S. Chen and Lefebvre, A. H., "Spray Cone Angle of Effervescent Atomizers," Atomization and Sprays, vol. 4, pp.291-301, 1994.

[34] 楊坤和，研究型氣助式噴嘴之噴霧特性研究，國立成功大學航太所碩士論文，1992。

[35] 徐明生，雙流體式平面噴嘴霧化特性之研究，國立成功大學航太所碩士論文，1995。

[36] 王承光，氣助式及氣衝式平面噴嘴中霧化空氣對噴霧特性之研究，國立成功大學航太所碩士論文，1996。

[37] Mates, S. P., and Settles, G. S., "High-Speed Imaging of Liquid Metal Atomization by Two Different Close-Coupled Gas Atomization Nozzles," presented at the 1996 World Congress on Powder Metallurgy and Particulate Materials, Washington DC,June16-21, 1996.

[38] Anderson, I. E., and Terpstra, R. L., “Progress toward gas atomization processing with increased uniformity and control,” Materials Science and Engineering：A, Vol.326, Issue 1, pp. 101-109, Mar. 15, 2002.

[39] 康煜昌，平面型液態金屬霧化器之霧化特性研究，國立成功大學航太所碩士論文，1998。

[40] 楊舒然，強制式液態金屬霧化器之控制參數研究，國立成功大學航太所碩士論文，1999。

[41] 楊哲睿，液態金屬在噴嘴不同長寬比下之霧化特性，國立成功大學航太所碩士論文，2002。

[42] 郭振展，液態金屬在噴嘴低長寬比下之霧化特性，國立成功大學航太所碩士論文，2003。

[43] Sedat Özbilen, “Influence of atomizing gas on particle shape of Al and Mg powder,” Powder Technology., Vol.102, Issue.2, Mar. 3, pp. 109-119, 1999.

[44] 王覺寬，康煜昌，徐明生，楊舒然，”氣助式平面型液態金屬霧化器特性研究。 ” 40th Conference on Aero. and Astro. Of ROC, Taichung, Taiwan, ROC, Dec, 1998.

[45] Box, G.E.P., Draper, W.G. and Hunter, J.S., Statistics for Experimenters, An Introduction to Design, Data Analysis and Model Building, John Wiley ＆Sons, 1978.

[46] Gupta A. K.、Lilley D. G. and Syred N., Swirl Flow, 1984.