基于主动喷注方式的后缘突扩凹腔激光诱导等离子体点火实验研究
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摘要
针对马赫数2.92,总压2.6MPa和总温1530K的超声速来流条件,基于主动喷注乙烯的燃料喷注方案,在后缘突扩凹腔燃烧室中开展了激光诱导等离子体点火实验研究。通过采集50kHz的CH*基自发辐射图像,详细观测了火焰传播过程并进而研究了主动式燃料喷注方案对点火过程的影响。研究表明,在激光诱导等离子体点火以后,CH*基强度沿时间的变化会呈现出不同的阶段性特征,大体可以分为四个不同的发展变化阶段(激光激发阶段、初始火焰阶段、过渡阶段和全局火焰阶段)。对于采用凹腔主动式燃料喷注方案,都会经历一个类似的初始火焰形成、减弱、增长和迅速发展成全局火焰的过程,区别在于采用凹腔后壁面燃料喷注方案的初始火焰要更加微弱,而且要经历一个难以观测到CH*基信号的初始火焰沉寂阶段。在全局当量比0.03～0.07的条件下,凹腔前壁面燃料喷注方案要比凹腔后壁面燃料喷注方案更加利于初始火焰的发展,但在形成全局火焰以后会引起较大的波动不利于火焰稳定。
Experimental investigation on the laser-induced plasma(LIP)ignition based on direct fueling schemes was conducted in an ethylene fueled model scramjet combustor with a rear-wall-expansion cavity in a Ma=2.92 supersonic inflow with a stagnation pressure of 2.6 MPa and a stagnation temperature of 1530 K.To study the effect of cavity direct fueling schemes on LIP ignition processes,flame motions were studied by recording the CH* chemiluminescence images at the frame rate of 50 kHz.It is indicated that there exists different stages during a LIP ignition process,which could be classified into four different periods as laser excitation,initial flame,transition and complete flame periods.As for the cavity direct fueling scheme,it is observed that there always exist similar initial flame formation,weakening,growing and fast transition processes.Furthermore,an initial flame quiescent phenomenon will occur under the cavity direct fueling scheme with rear-wall injection,during which the CH* signal is hardly to be recorded.At global equivalence ratios between 0.03 and 0.07,the cavity direct fueling scheme with fore-wall injection is more favorable for the initial flame propagation,however,it will also cause oscillations during the flame stabilization process.
Experimental investigation on the laser-induced plasma(LIP)ignition based on direct fueling schemes was conducted in an ethylene fueled model scramjet combustor with a rear-wall-expansion cavity in a Ma=2.92 supersonic inflow with a stagnation pressure of 2.6 MPa and a stagnation temperature of 1530 K.To study the effect of cavity direct fueling schemes on LIP ignition processes,flame motions were studied by recording the CH* chemiluminescence images at the frame rate of 50 kHz.It is indicated that there exists different stages during a LIP ignition process,which could be classified into four different periods as laser excitation,initial flame,transition and complete flame periods.As for the cavity direct fueling scheme,it is observed that there always exist similar initial flame formation,weakening,growing and fast transition processes.Furthermore,an initial flame quiescent phenomenon will occur under the cavity direct fueling scheme with rear-wall injection,during which the CH* signal is hardly to be recorded.At global equivalence ratios between 0.03 and 0.07,the cavity direct fueling scheme with fore-wall injection is more favorable for the initial flame propagation,however,it will also cause oscillations during the flame stabilization process.
引文
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[23]蔡尊,王振国,李西鹏,等.基于超声速气流中凹腔主动喷注的强迫点火方案研究[J].推进技术,2015,36(8):1186-1192.(CAI Zun,WANG Zhenguo,LI Xi-peng,et al.Investigation of Forced Ignition Scheme Based on Active Cavity Injection in a Supersonic Flow[J].Journal of Propulsion Technology,2015,36(8):1186-1192.)
[24]蔡尊,王振国,孙明波,等.超声速气流中凹腔主动喷注的强迫点火过程实验研究[J].推进技术,2014,35(12):1661-1668.(CAI Zun,WANG Zhenguo,SUN Ming-bo,et al.Experimental Study of Forced Ignition Process with Active Cavity Injection in a Supersonic Flow[J].Journal of Propulsion Technology,2014,35(12):1661-1668.)
[2]Curran E T.Scramjet Engines:The First Forty Years[J].Journal of Propulsion and Power,2011,17(6):1138-1148.
[3]Mathur T,Billig F.Supersonic Combustion Experiments with a Cavity-Based Fuel Injector[J].Journal of Propulsion and Power,2001,17(6):1305-1312.
[4]Barnes F W,Segal C.Cavity-Based Flameholding for Chemically-Reacting Supersonic Flow[J].Progress in Aerospace Sciences,2015,76:24-41.
[5]Wang Z,Wang H,Sun M.Review of Cavity-Stabilized Combustion for Scramjet Applications[J].Journal of Aerospace Engineering,Proceedings of the Institution of Mechanical Engineers Part G,2014,228:2718-2735.
[6]Cai Z,Zhu J,Sun M,et al.Spark-Enhanced Ignition and Flame Stabilization in an Ethylene-Fueled Scramjet Combustor with a Rear-Wall-Expansion Geometry[J].Experimental Thermal and Fluid Science,2018,92:306-313.
[7]Kitagawa T,Moriwaki A,Murakami K,et al.Ignition Characteristics of Methane and Hydrogen Using a Plasma Torch in Supersonic Flow[J].Journal of Propulsion and Power,2003,19(5):853-858.
[8]Do H,Cappelli M A,Mungal M G.Plasma Assisted Cavity Flame Ignition in Supersonic Flows[J].Combustion and Flame,2010,157:1783-1794.
[9]Brieschenk S,O'Byrne S,Kleine H.Ignition Characteristics of Laser-Ionized Fuel Injected into a Hypersonic Crossflow[J].Combustion and Flame,2014,161:1015-1025.
[10]Phuoc T X.Laser-Induced Spark Ignition Fundamental and Applications[J].Optics and Lasers in Engineering,2006,44:351-397.
[11]Brieschenk S,O'Byrne S,Kleine H.Laser-Induced Plasma Ignition Studies in a Model Scramjet Engine[J].Combustion and Flame,2013,160:145-148.
[12]Jacobsen L S,Carter C D,Jackson T A.Plasma-Assisted Ignition in Scramjets[J].Journal of Propulsion and Power,2008,24(4):641-654.
[13]Yang L,An B,Li X,et al.Characterization of Successive Laser Induced Plasma Ignition in an Ethylene Fuelled Model Scramjet Engine[C].Xiamen:21st AIAA International Space Planes and Hypersonic Technologies Conferences,2017.
[14]An B,Wang Z,Yang L,et al.Experimental Investigation on the Impacts of Ignition Energy and Position on Ignition Processes in Supersonic Flows by Laser-Induced Plasma[J].Acta Astronautica,2017,137:444-449.
[15]Cai Z,Yang Y,Sun M,et al.Experimental Investigation on Ignition Schemes of a Supersonic Combustor with the Rearwall-Expansion Cavity[J].Acta Astronautica,2016,123:181-187.
[16]Wang Z,Cai Z,Sun M,et al.Large Eddy Simulation of the Flame Stabilization Process in a Scramjet Combustor with Rearwall-Expansion Cavity[J].International Journal of Hydrogen Energy,2016,41:19278-19288.
[17]Cai Z,Wang Z,Sun M,et al.Effect of Combustor Geometry and Fuel Injection Scheme on the Combustion Process in a Supersonic Flow[J].Acta Astronautica,2016,129:44-51.
[18]Cai Z,Wang Z,Sun M,et al.Large Eddy Simulation of the Flame Propagation Process in an Ethylene Fuelled Scramjet Combustor in a Supersonic Flow[C].Xiamen:21st AIAA International Space Planes and Hypersonics Technologies Conference,2017.
[19]Cai Z,Zhu X,Sun M,et al.Experiments on Flame Stabilization in a Scramjet Combustor with a Rear-Wall-Expansion Cavity[J].International Journal of Hydrogen Energy,2017,42:26752-26761.
[20]Milligan R,Eklund D,Wolff M,et al.Dual Mode Scramjet Combustor:Analysis of Two Configurations[C].Oriando:48th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition,2010.
[21]Milligan R,Liu J,Tam C J,et al.Dual-Mode Scramjet Combustor:Numerical Sensitivity and Evaluation of Experiments[C].Nashville:50th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition,2012.
[22]Milligan R,Mathur T.Dual-Mode Scramjet Combustor:Numerical Analysis of Two Flowpaths[J].Journal of Propulsion and Power,2011,27(6):1317-1319.
[23]蔡尊,王振国,李西鹏,等.基于超声速气流中凹腔主动喷注的强迫点火方案研究[J].推进技术,2015,36(8):1186-1192.(CAI Zun,WANG Zhenguo,LI Xi-peng,et al.Investigation of Forced Ignition Scheme Based on Active Cavity Injection in a Supersonic Flow[J].Journal of Propulsion Technology,2015,36(8):1186-1192.)
[24]蔡尊,王振国,孙明波,等.超声速气流中凹腔主动喷注的强迫点火过程实验研究[J].推进技术,2014,35(12):1661-1668.(CAI Zun,WANG Zhenguo,SUN Ming-bo,et al.Experimental Study of Forced Ignition Process with Active Cavity Injection in a Supersonic Flow[J].Journal of Propulsion Technology,2014,35(12):1661-1668.)