同軸噴注器使用液體氧化劑與氣體燃料進行混合燃燒，為了探討液體黏滯係數及表面張力對於霧化效果的影響，本研究使用50wt%甘油水溶液以及15vol%乙醇水溶液為工作流體進行實驗，以了解霧化角、核心粒徑、粒徑分布之變化。本研究採用三種實驗方法觀察同軸霧化現象：由平面雷射激發螢光（Planar Laser Induced Fluorescence, PLIF）觀測系統所得到的二維質量機率分布計算霧化角；利用粒徑分析儀觀測粒徑分布，並計算核心粒徑；使用高速攝影系統拍攝核心液柱之分解過程及變化。實驗結果顯示，降低噴流表面張力使液柱表面不穩定波較容易形成，粒徑空間分布較不均勻但平均粒徑下降，對於霧化角之影響不大。提高噴流黏滯係數將使霧化角變大、液柱表面擾動較小，液柱在下游以膜狀(Membrane)破碎，大片狀薄膜受到氣體剪切碎裂，使核心液柱快速斷裂，核心粒徑下降快速，且粒徑分布均勻。

Coaxial injector is mainly used in the mixing and combustion between liquid oxidizer and gaseous fuel. This research focuses on the effects of viscosity and surface tension of the liquid on the spray formation from a self-designed coaxial injector. The test solutions include pure water, 50wt% glycerin in water, and ethanol 15vol% ethanol in water. The spray angle, drop size distribution, core SMD (SMD0.35), and the jet surface instability waveform of the liquid sprays are analyzed by Planar Laser Induced Fluorescence (PLIF) technique, Malvern droplet analyzer, and high-speed photography, respectively. The results show that an earlier appearance of instable wave formation on jet surface and a smaller SMD distribution of the downstream spray are observed by decreasing the surface tension of the liquid jet, however, the spray angle is shown to be insensitive to surface tension variation. By increasing the liquid viscosity, the liquid jet is more stable and less surface wave formation was observed. The jet breaks up in membrane-type into a spray. The spray has a smaller core SMD and a more even spatial distribution of the droplet size.

1.Lefebvre,A.H,”Atomization and Spray”,Hemisphere Publishing Corporation,pp3-60,1989

2.C. Engelbert, Y. Hardalupas and J. H. Whitelaw,” Breakup Phenomena in Coaxial Airblast Atomizers”, Mathematical and Physical Sciences, Vol. 451, No. 1941, Osborne ReynoldsCentenary Volume (Oct. 9, 1995), pp. 189-229

3.Weber, C., “On the Disruption of Liquid Jets”, Math. Mech., Vol. 11, pp. 136, 1931

4.Mayer, W. O. H., “Coaxial atomization of a round liquid jet in a high speed gas stream: A phenomenological study”, Experiments in Fluids, Vol.16, pp 401-410, 1994

5.Ferraro, M., Kujala, R. J., Thomas, J.-L., Glogowski, M. J. and Micci, M. M., “Effects of GH2/LOX Velocity and Momentum Ratios on Shear Coaxial Injector Atomization”, Journal of Propulsion and Power, Vol. 18, No. 1: Technical notes, 2001

6.Hanson, A. R., Domich, E. G., and Adams, H. S., “Shock Tube Investigation of the breakup of Drops by Air Blasts”, Phys. Fluids, Vol. 6, pp. 1070-1080,1963.

7.Lasheras, J.C. and Hoppfinger, E. J., Liquid Jet Instability and Atomization in a Coaxial Gas Stream, Annual Review Fluid Mechanics, Vol. 32, 2000, pp. 275-308.

8.袁曉峰，林建國，唐紹文,”剪切式同軸噴注器之霧化觀察分析 “成功大學航太所碩士論文,中華民國100年.

9.袁曉峰，蔡博宇,”完全發展模式下雙衝擊式噴霧之霧化觀察“
成功大學航太所碩士論文,中華民國100年

10.Branam, R. and Mayer, W.: Atomization Characteristics on the Surface of Round Liquid Jet, Experiments in Fluids Vol. 36, 2004, pp. 528-539.

11. Wu P-K; Tseng L-K; Faeth G. M.: Primary breakup in gas/liquid mixing layers for turbulent liquids, Atomization and Sprays, Vol. 2, pp. 295-317

12.Z. Farrago,N. Chigier, “Morphological classification of disintegration of round liquid jets in a coaxial air stream”, Atomization and sprays vol.2,pp.137-153, 1992

13.Yu Pan and Kazuhiko suga ,”A numerical study on the breakup process of laminar liquid jets into a gas”,Physics of Fluids 18, 2006