在本研究中，吾人針對預成膜噴霧現象的基礎學理進行了實驗研究。從國防獨立自主的觀點來看，相關國防工業基礎技術始終扮演著重要的角色，我們也可以理解到高性能戰鬥機通常需要強大的渦輪發動機來驅動；不僅如此，在本世紀中另外一個重要的課題就是減少渦輪發動機的二氧化碳和有毒污染物的排放。眾所周知，推進工具的性能主要都取決於燃燒前的燃料和空氣混合，因此，在本研究中將以一個簡化的預膜噴注器模型進行設計與分析，該噴注器俱備有兩個同心環形的出口，其內圈和外圈分別是液體和空氣的流出的地方。此噴嘴的氣助氣流係由不同的旋流器進行氣流的調節以達到產生不同旋流數的目的。在此噴嘴的操作中，液膜會被旋轉的空氣所撕裂，進而可以產生更為細小的液滴。在研究中，透過數值模擬評估噴注器內部流道中的漩渦數，並使用噴霧可視化方法、Malvern粒徑分析技術和平面痕劑誘發螢光法來分析並且量測噴霧。在本論文中展示本研究所設計製作噴嘴之噴霧外觀、噴霧型樣、液滴尺寸分佈以及質量分佈等重要資訊；此外，根據這些實驗結果，也初步提出了經驗公式以預測破裂長度。這些基礎理論和技術的了解，相信能夠進一步成為高性能噴注器設計及其性能控制之基礎。

In the present study, the fundamental studies on the pre-filmed spray phenomena were experimentally investigated. From the point of view of the independence of the defense issues, fundamental technologies always play a significant role. A high-performance fighter needs powerful turbofan engines. Moreover, reducing carbon dioxide emissions and toxic pollutants for turbofan engines is also an essential issue in the current century. It has been well known that the performance of the propulsion devices is dominated by the fuel and air preparation prior to combustion. Hence, a simplified pre-film sprayer model was designed and evaluated in the present study. This sprayer was equipped with two concentric annular outlets. The inner ring and the outer ring are the outlets for liquid and air, respectively. The blast air stream is tuned by the swirler to generate the swirling flow with different swirl numbers. The liquid film was broken down by the swirling air, and the fine droplets can be generated. The swirl number in the channel of the sprayer was evaluated by numerical simulation, and the spray was evaluated using spray visualization methods, Malvern spray sizing, and Planar Tracer Laser-induced Fluorescence. The spray appearance, patterns, droplet size distribution, mass distributions were demonstrated in this thesis. In addition, according to the measured results, the empirical formula was also proposed to estimate the breakup length of the liquid film. It is believed that understanding the fundamental theories and technologies will serve as the basis for further high-performance sprayer design and its control of the performance.

[1] A. H. Lefebvre and V. G. McDonell, Atomization and sprays. CRC press, 2017.
[2] A. H. Lefebvre, Gas turbine combustion. CRC press, 1998.
[3] O. Klüsener, "The injection process in compressorless diesel engines," VDI Z, vol. 77, no. 7, pp. 107-110, 1933.
[4] L. Rayleigh, "On the instability of jets," Proceedings of the London mathematical society, vol. 1, no. 1, pp. 4-13, 1878.
[5] C. Weber, "Disintegration of liquid jets," Z. Angew. Math. Mech., vol. 1, pp. 136-159, 1931.
[6] W. v. Ohnesorge, "The formation of drops by nozzles and the breakup of liquid jets," UT Faculty/Researcher Works, 2019.
[7] R. A. Castleman, "The mechanism of the atomization of liquids," 1931.
[8] R. D. Reitz, Atomization and other breakup regimes of a liquid jet. Princeton University, 1978.
[9] E. Giffen and A. Muraszew, The atomization of liquid fuels. Chapman & Hall, 1953.
[10] A. Haenlein, "Disintegration of a liquid jet," 1932.
[11] N. Dombrowski and W. Johns, "The aerodynamic instability and disintegration of viscous liquid sheets," Chemical Engineering Science, vol. 18, no. 3, pp. 203-214, 1963.
[12] R. Fraser, "Research into the performance of atomizers for liquids," Imp. Coll. Chem. Eng. Soc. J., vol. 7, pp. 52-68, 1953.
[13] R. Fraser, "Liquid fuel atomization," in Symposium (International) on Combustion, 1957, vol. 6, no. 1: Elsevier, pp. 687-701.
[14] R. Fraser, P. Eisenklam, N. Dombrowski, and D. Hasson, "Drop formation from rapidly moving liquid sheets," AIChE Journal, vol. 8, no. 5, pp. 672-680, 1962.
[15] N. Dombrowski and R. Fraser, "A photographic investigation into the disintegration of liquid sheets," Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences, vol. 247, no. 924, pp. 101-130, 1954.
[16] J. L. York, "The mechanism of disintegration of liquid sheets," Trans. ASME, vol. 75, pp. 1279-1286, 1953.
[17] G. Solero, "Experimental characterization of the isothermal mixing process in a model of a natural gas swirl combustor," in 50th Congresso Nazionale ATI, 1995.
[18] M. Alecci, G. Cammarata, and G. Petrone, "Analysis and Modelling of a low NOx'Swirl Burner'," in Comsol Multiphysics Conference 2005: Proceedings and User Presentations CD, 2006.
[19] K. Khanafer and S. Aithal, "Fluid-dynamic and NOx computation in swirl burners," International Journal of Heat and Mass Transfer, vol. 54, no. 23-24, pp. 5030-5038, 2011.
[20] Q. Xu et al., "Performance Analysis of Novel Flue Gas Self-Circulated Burner Based on Low-NOx Combustion," Journal of Energy Engineering, vol. 146, no. 2, p. 04019041, 2020.
[21] B. Déjean, P. Berthoumieu, and P. Gajan, "Experimental study on the influence of liquid and air boundary conditions on a planar air-blasted liquid sheet, Part I: Liquid and air thicknesses," International Journal of Multiphase Flow, vol. 79, pp. 202-213, 2016.
[22] L. Xu, Z. Xia, M. Zhang, Q. Du, and F. Bai, "Experimental research on breakup of 2D power law liquid film," Chinese Journal of Chemical Engineering, vol. 23, no. 9, pp. 1429-1439, 2015.
[23] B. Déjean, P. Berthoumieu, and P. Gajan, "Experimental study on the influence of liquid and air boundary conditions on a planar air-blasted liquid sheet, Part II: Prefilming zone length," International Journal of Multiphase Flow, vol. 79, pp. 214-224, 2016.
[24] M. M. Tareq, R. A. Dafsari, S. Jung, and J. Lee, "Effect of the physical properties of liquid and alr on the spray characteristics of a pre-filming airblast nozzle," International Journal of Multiphase Flow, vol. 126, p. 103240, 2020.
[25] T. Inamura, N. Katagata, H. Nishikawa, T. Okabe, and K. Fumoto, "Effects of prefilmer edge thickness on spray characteristics in prefilming airblast atomization," International Journal of Multiphase Flow, vol. 121, p. 103117, 2019.
[26] H. Zhao and H. Liu, "Breakup Morphology and Mechanisms of Liquid Atomization," in Environmental Impact of Aviation and Sustainable Solutions: IntechOpen, 2019.
[27] J. M. Beér, "Combustion aerodynamics," in Combustion Technology: Elsevier, 1974, pp. 61-89.
[28] R. Tate, "Equipment and design—spray patternation," Industrial & Engineering Chemistry, vol. 52, no. 10, pp. 49A-58A, 1960.