超燃衝壓引擎為當代吸氣式發動機中最具發展潛力與未來趨勢之推進系統，其特點為自由流能在燃燒室中維持超音速狀態，卻也因而需在極短時間內與燃料相互混合並進行燃燒反應，因此有時會加入凹槽、支架等助焰機構以提升燃燒效率，燃燒室內之流場物理現象也複雜許多。本研究將根據計算流體力學軟體ANSYS FLUENT，對具凹槽機構之燃燒室進行超音速非反應及燃燒反應流場之數值模擬分析，並使用液態碳氫燃料JP-4作為燃料噴注。
在超音速非反應流場參數分析中，除了考量在燃料總量相同下，槽外單噴注(16.5g/s)與槽內外雙噴注(12.0+4.5g/s)注入流場之差異性外，亦對雙噴注之槽內不同噴射角度做相互比較。結果顯示槽外單噴注注入縱使因較大質量流率，得以使噴注穿透高度較高，但在凹槽內之燃料氣莫耳分率與燃料駐留在燃燒室之時間卻不及槽內外雙噴注機構；另外，隨著槽內噴注噴射角度 (0、45、60度) 增加，氣流流經凹槽向下擴張的程度亦減小，槽內迴流區上方之剪切層也有明顯抬升，燃料進入迴流區碎裂氣化比例也跟著降低。在雙噴注超音速燃燒反應流場分析中，則是藉上(槽外噴注前方)、中(凹槽底部)、下游(後傾角頂點後方)三個不同點火位置，比較燃燒室之產物分布、燃燒效率與總壓損失等等。可以預測到燃燒室之壓力最大值約為250kPa，而最高溫則從點火的2340K上升至約莫2800K左右，且亦有生成燃燒產物NO，得以證實其確實有燃燒反應發生。以上游及下游點火來看，OH與H2O等化合物多分布在燃燒之高溫區，且貼近壁面向下游延伸；而中游點火之化合物則是主要分布於凹槽內。此外，由於凹槽內流場流速較低，因此中游點火(具初始速度)會造成槽內產生數個迴流區，除了增加駐焰效果，燃燒效率相較於上、下游點火也均來得高，約可達至22.01%左右；然而，卻也帶來大約31.86%的總壓損失。

ANSYS FLUENT numerical simulation software is employed in this study to analyze supersonic combustion flow phenomena with dual liquid fuel injection and a cavity mechanism. First, this study focuses on parameter analyses of a non-reactional flow in order to determine a suitable allocation of fuel for the combustion chamber. Then, following Wang et al. (2015), the numerical simulation combustion results are compared with the experimental wall pressure distribution, and the accuracy of the proposed numerical method is proven. Finally, three ignition positions in the chamber are established to analyze the effects of ignition position on supersonic combustion reactive flow.
First, in terms of the supersonic non-reactive flow, the parameter analysis was focused on the differences between single/dual fuel injection and the influences of the injection angles. The results showed that under the same mass flow rate conditions, dual fuel injection can be anticipated to obtain higher combustion efficiency owing to the wide range of fuel diffusion in the cavity. On the other hand, the ratio of the fuels going into internal recirculation can be changed by the different injection angles in the cavity. This also means that a greater injection angle in the cavity results in less fuel in the cavity recirculation zone. Second, after verifying the numerical combustion method, we predicted the effects of three different ignition positions on the supersonic combustion flow: (up: the front of the outer injection area; middle: the cavity bottom; down: the downstream of the combustion chamber). Owing to the combustion exothermic reaction, the temperature reached approximately 2800K. In addition, the pressure rose to 250kPa, and most of the combustion products were distributed in the high temperature zone. Furthermore, midstream ignition caused many recirculation zones to occur in the cavity that in turn kept the flame burning. To determine the combustion efficiency and total pressure loss, we referred to the definition from Kim et al. (2004). The results showed that combustion efficiency in middle ignition was the highest and reached approximately 22.01%, with a total pressure loss of 31.86%.

【1】 Lewis, M. J., 2001,“Significance of Fuel Selection for Hypersonic Vehicle Range,”Journal of Propulsion and Power, Vol.17, No.6, pp.1214-1221.
【2】 Powell, O. A., Edwards, J. T., Norris, R. B., Numbers, K. E., and Pearce, J. A., 2001,“Development of Hydrocarbon-Fueled Scramjet Engines: The Hypersonic Technology Program,”Journal of Propulsion and Power, Vol.17, No.6, pp.1170-1176.
【3】 Tetlow, M. R., and Doolan, C. J., 2007,“Comparison of Hydrogen and Hydrocarbon-Fueled Scramjet Engine for Orbital Insertion,”Journal of Spacecraft and Rockets, Vol.44, No.2, pp.365-373.
【4】 Manna, P., Behera, R., and Chakraborty, D., 2008,“Liquid-Fueled Strut-Based Scramjet Combustor Design: a Computational Fluid Dynamics Approach,”Journal of Propulsion and Power, Vol.24, No.2, pp.274-281.
【5】 Lin, K. C., Kirkendall, K. A., Kennedy, P. J., and Jackson, T. A., 1999,“Spray Structures of Aerated Liquid Fuel Jets in Supersonic Crossflows,”35th AIAA Joint Propulsion Conference and Exhibit, AIAA1999-2374.
【6】 Yu, G., Li, J. G., Yang, S. R., Yue, L. J., and Zhang, X. Y., 2002,“Investigation of Liquid Hydrocarbon Combustion in Supersonic Flow Using Effervescent Atomization,”38th AIAA Joint Propulsion Conference and Exhibit, AIAA2002-4279.
【7】 Yue, L. J., and Yu, G., 2003,“Studies on Spray Characteristics of Barbotaged Atomizer,”Journal of Propulsion Technology, Vol.24, No.4, pp.348-352.
【8】 Balasubramanyam, M. S., and Chen, C. P., 2006,“Evaporating Spray in Supersonic Streams including Turbulence Effects,”AIAA Aerospace Sciences Meeting and Exhibit.
【9】 Yue, L. J., and Yu, G., 2004,“Numerical Simulation of Kerosene Spray in Supersonic Cross Flow,”Journal of Propulsion Technology, Vol.25, No.1, pp.11-14.
【10】Li, P., Wang, Z., Bai, X. S., Wang, H., Sun, M., Wu, L., Liu, C., 2019, “Three-Dimensional Flow Structures and Droplet-Gas Mixing Process of a Liquid Jet in Supersonic Crossflow,” Aerospace Science and Technology, Vol. 90, pp.140-156.
【11】 Im, K. S., Lin, K. C., and Lai, M. C., 2005,“Spray Atomization of Liquid Jet in Supersonic Cross Flows,”43rd AIAA Aerospace Sciences Meeting and Exhibit, AIAA2005-732.
【12】 劉靜, 徐旭, 2010,“超音速橫向氣流中燃料霧化的數值模擬,”北京航空航天大學學報, Vol.36, No.10.
【13】 Yang, D. C., Zhu, W. B., Chen, H., Guo, J. X., and Liu, J. W., 2014,“Model the Secondary Breakup of a Liquid Jet in Supersonic Cross Flows,”Journal of Harbin Engineering University, Vol.35, No.1, pp.62-68.
【14】 Zhu, L., Qi, Y.Y., Liu, W.L., Xu. B.J., Ge. J.R., Xuan, X.C., Jen, T.C., 2016, “Numerical Investigation of Scale Effect of Various Injection Diameters on Interaction in Cold Kerosene-Fueled Supersonic Flow,” Acta Astronautica, Vol. 129, pp.111-120
【15】 楊成麥, 2019,“噴霧模式之參數對液態燃料注入超音速流場數值擬分析影響之研究,”國立成功大學航空太空工程學系碩士論文.
【16】 沈雅蓁, 2015, “側向雙垂直噴注於超音速空氣流場之霧化混合探討,” 成功大學航空太空工程學系碩士論文.
【17】 Chenault, C. F., and Beran, P. S., 1998,“k- and Reynolds Stress Turbulence Model Comparisons for Two-Dimensional Injection Flows,”AIAA Journal, Vol. 36, pp.1401-1412.
【18】 Menter, F. R., 1994,“Two-Equation Eddy-Viscosity Turbulence Models for Engineering Applications,”AIAA Journal, Vol.32, pp.1598-1605.
【19】 Liu, O. Z., Cai, Y. H., Hu, Y. L., Liu, J. H., and Ling, W. H., 2007,“The Turbulence Models for Numerical Analysis of Liquid Kerosene Supersonic Combustion,”Acta Aerodynamica Sinica, Vol.25, pp.362-367.
【20】 宋緯倫, 2010,“不同紊流模式對超音速流場數值模擬結果之影響,”國立成功大學航空太空工程學系碩士論文.
【21】 Aso, S., Okuyama, S., Kawai, M., and Ando, Y., 1991,“Experimental Study on Mixing Phenomena in Supersonic Flows with Slot Injection,”29th Aerospace Sciences Meeting, AIAA1991-16.
【22】Gruber, M. R., Bauerle, R. A., Mathur, T., and Hsu, K. Y., 2001,“Fundamental Studies of Cavity-Based Flameholder Concepts for Supersonic Combustors,”Journal of Propulsion and Power, Vol.17, No.1, pp.146-153
【23】Gruber, M. R., Donbar, J. M., Carter, C. D., and Hsu, K. Y., 2004,“Mixing and Combustion Studies Using Cavity-Based Flameholders in a Supersonic Flow,”Journal of Propulsion and Power, Vol.20, No.5, pp.769-778.
【24】Barnes, F. W., Segal, C., 2015, “Cavity-Based Flameholding for Chemically-Reacting Supersonic Flows,” Progress in Aerospace Sciences, Vol. 76, pp. 24-41.
【25】Liu, O. Z., Hu, Y. Z., Cai, Y. H., Liu, J. H., and Ling, W. H., 2003,“Overview of Flameholders of Cavities in Supersonic Combustion,”Journal of Propulsion Technology, Vol.24, No.3, pp.265-271.
【26】Yu, G., Li, J. G., Chang, X. Y., Chen, L. H., and Sung, C. J., 2003,“Fuel Injection and Flame Stabilization in a Liquid-Kerosene-Fueled Supersonic Combustor,”Journal of Propulsion and Power, Vol.19, No.5, pp.885-893.
【27】鄭瑞圻, 2013,“使用液態碳氫燃料之超音速燃燒流場模擬分析,”國立成功大學航空太空工程學系碩士論文.
【28】郭建嘉, 2017,“凹槽機構對液態燃料噴注之超音速燃燒流場影響之數值模擬分析,”國立成功大學航空太空工程學系碩士論文.
【29】Cuppoletti, D., Ombrello, T., Carter, C., Hammack, S., Lefkowitz, J., 2020,“Ignition Dynamics of a Pulse Detonation Igniter in a Supersonic Cavity Flameholder,”Combustion and Flame, Vol.215, pp.376-388.
【30】Li, A., Ge, Y., Wei, X., Li, T., 2016,“Mixing and Combustion Modeling of Hydrogen Peroxide/Kerosene Shear-Coaxial Jet Flame in Lab-Scale Rocket Engine,”Aerospace Science and Technology, Vol.56, pp.148-154.
【31】郭俊淇, 2016, “W2(煤油基)/過氧化氫推進劑液旋噴注機構之自燃特性分析,” 成功大學航空太空工程學系碩士論文.
【32】ANSYS FLUENT, 2013,“Ansys Fluent 15.0 Theory Guide,”ANSYS Inc.
【33】Iannetti, A. C., and Moder, J. P., 2010,“Comparing Spray Characteristics from Reynolds Averaged Navier-Stokes (RANS) and National Combustion Code (NCC) Calculations Against Experimental Data for a Turbulent Reacting Flow,”48th Aerospace Sciences Meeting, AIAA-2010-578.
【34】Jarosław, M., Konrad, Ś., Massimo, S., Pierluigi, L., 2011,“Advanced Methods of Solid Oxide Fuel Cell Modeling,” Springer
【35】蔡忠恩, 2019, “超音速流場之凹槽內外噴注特性觀察,” 成功大學航空太空工程學系碩士論文.
【36】Wang, L., Qian, Z. S., and Gao, L. J., 2015,“Numerical Study of the Combustion Field in Dual-Cavity Scramjet Combustor,”Procedia Engineering, Vol.99, pp.313-319.
【37】 Ranz, W. E., and Marshall, W. R., Jr., 1952,“Evaporation from Drops, Part II,”Chemical Engineering Progress Magazine, Vol.48, pp.173-180.
【38】 CAMEO Chemicals NOAA
【39】 Kim, K. M., Baek, S. W., Han, C. Y., 2004,“Numerical Study on Supersonic Combustion with Cavity-Based Fuel Injection,” International Journal of Heat and Mass Transfer, Vol.47, pp.271-286.