超音速燃燒衝壓引擎是現今航太領域中最具有發展潛力以及未來趨勢之推進系統。這個推進系統特色是氣流在進入燃燒室中維持著超音速狀態，以避免進入燃燒室之氣流溫度過高以及過多壓力損失，卻也導致需要在極短時間內將氣流與燃料相互均勻混合並進行燃燒反應。為了克服這個問題，可在燃燒室裝置駐焰機構如凹槽，使燃燒室有低速迴流區以讓燃燒穩定進行。因此，本研究為了探討凹槽模組之參數對超音速燃燒反應流場之影響，使用計算流體力學軟體ANSYS FLUENT對具有加裝凹槽機構之燃燒室進行超音速燃燒反應流場之數值模擬分析。本研究模擬分析加裝凹槽之燃燒室，具有槽外以及槽內燃料噴注。槽外噴注口位置在凹槽前方15mm處，其直徑為0.5mm，噴注質量流率為12g/s。在槽外噴注參數不改變狀況下，本研究針對槽內噴注之不同噴注參數如：噴注口直徑、噴注口數量、噴注口位置及噴注質量流率等，進行超音速燃燒反應流場之敏感性分析。
本研究模擬顯示，在槽內噴注口直徑方面，槽內噴注口直徑從0.5mm改成0.3mm時，因噴注噴射速度變快，會使液柱和氣體之相對速度更大，進而讓液柱更容易受到氣流影響而破碎成小液滴，因此燃料更容易汽化，並和空氣混合，以便進行燃燒。故槽內噴注口直徑從0.5mm改為0.3mm時更能維持燃燒之穩定進行。在槽內噴注口數量方面，當槽內單噴注改為槽內雙噴注，但噴注總質量流率不變時，因槽內雙噴注之每個噴注質量流率會降低，同時讓每個噴注噴射速度隨著降低，使液態碳氫燃料很難噴射到迴流區中心，而且會受到迴流區外圍之氣流影響而帶離槽外，而更難進行燃燒。故噴注口數量從單噴注改為槽內雙噴注更難維持燃燒之穩定進行。不過槽內雙噴注可以改善碳氫燃料集中在凹槽中間之問題，故以槽內雙噴注為基準來進行不同參數分析。在槽內噴注口位置方面，槽內噴注口位置從凹槽前壁面噴注改為從凹槽斜壁面噴注，由於噴注位置不同，都會使液態碳氫燃料會受到迴流區外圍之氣流方向影響，差別是從凹槽前壁面噴注是氣流帶著燃料帶離凹槽；從凹槽斜壁面噴注是氣流帶入凹槽，讓碳氫燃料更有效滯留在燃燒室之低速區，以便進行燃燒。故槽內噴注口位置從凹槽前壁面噴注改為從凹槽斜壁面噴注更能維持燃燒之穩定進行。但是當噴注質量流率增加，會讓燃料噴到槽內外氣流交界處，促使燃料和空氣混合不彰，導致不能維持燃燒之穩定進行。在槽內總噴注質量流率方面，槽內總噴注質量流率從1g/s改為2g/s，因噴注噴射速度更快，使液態碳氫燃料更靠近迴流區中心，以便進行燃燒；槽內噴注總質量流率從2g/s改為3g/s，同樣因噴注噴射速度更快，使液態碳氫燃料剛好噴射到迴流區中心，以便進行燃燒。故內噴注總質量流率從1g/s逐漸改為3g/s時更能維持燃燒之穩定進行。但槽內噴注總質量流率從3g/s改為4g/s，反而因槽內液態碳氫燃料過量，使燃料和空氣更難混合而無法點燃，使燃燒反應無法順利進行。
總結來說，槽內噴注口直徑從0.5mm改成0.3mm時，因噴注噴射速度更快，使燃料更能破碎成小液滴，同時讓燃料和空氣混合，因此駐焰效果更佳。槽內單噴注改為槽內雙噴注時，因噴注總質量流率分成二等分，讓噴注噴射速度降低，使液態碳氫燃料受到迴流區外圍之氣流影響帶離凹槽，因此駐焰效果更差。槽內噴注口位置從凹槽前壁面噴注改為凹槽斜壁面噴注，噴注噴射速度不夠快，會使碳氫燃料會受到迴流區外圍之氣流影響而帶入凹槽中，因此駐焰效果更佳。槽內噴注總質量流率從1g/s逐漸改為4g/s時，調整至3g/s時因噴注噴射速度更快，使液態碳氫燃料剛好噴射到迴流區中心，因此駐焰效果最佳，但調整至4g/s時卻因槽內液態碳氫燃料過量，使燃料和空氣更難混合而無法點燃。，因此槽內噴注口位置從凹槽前壁面噴注改為凹槽斜壁面噴注更能維持燃燒之穩定進行。在槽內總噴注質量流率方面，槽內總噴注質量流率從1g/s改為2g/s，因噴注噴射速度變快，使液態碳氫燃料更難被氣流帶離凹槽；槽內噴注總質量流率從2g/s改為3g/s，同樣因噴注總質量流率更快，使液態碳氫燃料更不會受氣流影響，因此槽內噴注總質量流率從1g/s逐漸改為3g/s時更能維持燃燒之穩定進行。但槽內噴注總質量流率從3g/s改為4g/s，反之因槽內液態碳氫燃料過量而無法點燃，使燃燒反應無法進行。

In this study, the ANSYS FLUENT software for numerical simulation analysis was used for sensitivity analysis of different injection parameters that define the supersonic combustion flow field with dual liquid fuel injection and cavity mechanism. We first established the mesh model, boundary conditions, and ignition method, and then performed a sensitivity analysis for the injection nozzle diameter and number of injection nozzles in a situation in which single injection inside the cavity was adopted. Finally, we conducted a sensitivity analysis for the nozzle location and total injection mass flow rate in a situation in which dual injection inside the cavity was adopted. Thus, we determined the influence of the different parameters of injection inside the cavity on the supersonic combustion flow field.
First, concerning the injection nozzle diameter inside the cavity, when it is varied from 0.5 mm to 0.3 mm, the fuel can be broken up into more small droplets while the fuel mixes with air due to the faster injection speed. As a result, the flame-holding effect is better. Second, regarding the number of injection nozzles, when the single injection inside the cavity is changed to dual injection, the total injection mass flow rate is halved for each nozzle such that the injection speed becomes slower. Besides, the fuel is carried away from the nozzle by the airflow such that the flame-holding effect becomes worse. However, dividing the fuel equally between the two injection nozzles inside the cavity can alleviate the problem due to the fuel becoming concentrated after leaving the nozzle. Thus, in a situation in which dual injection occurs inside the cavity, different parameters were analyzed. Moreover, concerning the injection nozzle location, when the injection nozzle is located on the front wall of the cavity instead of on the inclined wall, the fuel can be carried into the cavity by airflow, resulting in a better flame-holding effect. Finally, in terms of the total injection mass flow rate, when this rate inside the tank is gradually varied from 1 g/s to 4 g/s, the injection speed at a mass flow rate of 3 g/s is faster such that the fuel can be injected right into the center of the cavity, resulting in an optimal flame-holding effect. However, when the total mass flow rate reaches 4 g/s, there is too much fuel inside the cavity, making it harder for the fuel and the air to mix and initiate ignition.

【1】 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.
【2】 Lewis, M. J., 2001,“Significance of Fuel Selection for Hypersonic Vehicle Range,”Journal of Propulsion and Power, Vol.17, No.6, pp.1214-1221.
【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】 Im, K. S., Lin, K. C., Lai, M. C., and Chon, M. S., 2011,“Breakup Modeling of a Liquid Jet in Cross Flow,”International Journal of Automotive Technology, Vol.12, pp.489-496.
【13】 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.
【14】 Yang, D. C., Zhu, W. B., Chen, H., Guo, J. X., and Liu, J. W., 2014,“Numerical Investigation of Scale Effect of Various Injection Diameters on Interaction in Cold Kerosene-Fueled Supersonic Flow, Vol.35, No.1, pp.62-68.
【15】 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
【16】 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.
【17】 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,” 國立成功大學航空太空工程學系碩士論文.
【18】 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.
【19】 Menter, F. R., 1994,“Two-Equation Eddy-Viscosity Turbulence Models for Engineering Applications,”AIAA Journal, Vol.32, pp.1598-1605.
【20】 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.
【21】 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
【22】 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.
【23】 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
【24】 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.
【25】 Barnes, F. W., Segal, C., 2015, “Cavity-Based Flameholding for Chemically-Reacting Supersonic Flows,” Progress in Aerospace Sciences, Vol. 76, pp. 24-41.
【26】 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.
【27】 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.
【28】 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.
【29】 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.
【30】 陳威廷, 2020, “雙噴注凹槽機構在超音速燃燒流場下之數值模擬分析” 國立成功大學航空太空工程學系碩士論文.
【31】 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.
【32】 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.
【33】 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,” 國立成功大學航空太空工程學系碩士論文.
【34】 劉啟文, 2020,“超音速燃燒流場點火與噴霧特性研究之數值模擬分析,” 國立成功大學航空太空工程學系碩士論文.
【35】 ANSYS FLUENT, 2013,“Ansys Fluent 15.0 Theory Guide,”ANSYS Inc.
【36】 Ranz, W. E., and Marshall, W. R., Jr., 1952,“Evaporation from Drops, Part II,”Chemical Engineering Progress Magazine, Vol.48, pp.173-180.
【37】 Jarosław, M., Konrad, Ś., Massimo, S., Pierluigi, L., 2011,“Advanced Methods of Solid Oxide Fuel Cell Modeling,” Springer
【38】 蔡忠恩, 2019, “超音速流場之凹槽內外噴注特性觀察,” 國立成功大學航空太空工程學系碩士論文.
【39】 石油產品規範,“航空燃油JP-4規範,” 台灣中油股份有限公司.
【40】 Tian Y., Yang S.,Xiao B.,Zhong F., Le J. , 2019 “Investigation of Ignition Characteristics in a Kerosene Fueled Supersonic Combustor,” Acta Astronautica, Volume 161, Pages 425-429
【41】 Zhang X., Qin L., Chen H., He X., Liu Y. , 2014 ,“Radical Recombination in a Hydrocarbon-Fueled Scramjet Nozzle,” Acta Astronautica, Volume 27, Pages 1413-1420.