Investigation of unburned/preheated area characteristics of a premixed flame under transverse acoustic excitation based on acetone and CH2O PLIF technology
-
摘要: 热声不稳定问题是航空航天动力装置发展中的难题之一,针对预混燃烧火焰的热声不稳定机理研究是解决实际发动机热声振荡难题的必经之路。采用丙酮/CH2O双组分PLIF同步测量技术对横向声波激励下的预混火焰特性进行了研究,获得了横向声波激励预混燃烧火焰中的未燃区/预热区分布变化情况。实验结果表明:随着激励声波声压级的增大和激励声波频率的减小,未燃区/预热区形貌的变化逐渐增强;同时,随着激励声波相位的变化,未燃区/预热区形貌呈周期性变化。对丙酮PLIF图像进行边界提取,获取了不同声波频率、声压级条件下的未燃区抬举高度、扩散面积。利用丙酮/CH2O双组分PLIF同步测量成功捕捉到典型声波频率、声压级下的火焰形貌演化过程,并分析了该典型工况下的火焰熄灭现象及其机制。
-
关键词:
- 丙酮/CH2O双组分PLIF /
- 声波激励 /
- 预混燃烧 /
- 混合特性 /
- 火焰形貌
Abstract: The thermoacoustic instability is one of the most difficult problems in the development of aerospace propulsion systems. The research on the thermoacoustic instability mechanism of premixed flame can be useful to realize and solve the thermoacoustic oscillation problems of the practical engines. The characteristics of the premixed flame excited by acoustic wave are investigated by the simultaneous acetone/CH2O planar laser-induced fluorescence(PLIF) technique, and the variation of unburnt zone and preheating zone is acquired. It is shown that the effect of the acoustic wave on the flame is more obvious at lower frequency and higher Sound Pressure Level (SPL). As the frequency decreases and SPL increases, the change of the flow structure gradually aggravates. It is also found that the morphology of unburned zone/preheating zone changes periodically with the acoustic wave phase. The edge of acetone PLIF images is extracted, and the dependence of the lifting height, diffusion area of the premixed gas on the acoustic wave frequency and the SPL is obtained. The evolution process of the flame morphology under typical acoustic frequency and pressure level is acquired by the simultaneous acetone/CH2O PLIF images. The phenomenon and mechanism of combustion flameout under typical acoustic condition are analyzed. -
表 1 层流预混燃具实验工况
Table 1. Laminar premixed combustion conditions
$Q_{{\rm{CH}}_4} $
/(L·min–1)Qacetone
/(L·min–1)Qair
/(L·min–1)Φ v
/(m·s–1)Re 1.16 0.0008 10 1.1 1.05 1004 表 2 层流预混燃具实验工况声压级
Table 2. SPL of laminar premixed combustion conditions
f/Hz A1/dB A2/dB A3/dB A4/dB 50 120.1 122.5 124.1 125.6 70 120.1 122.5 124.1 — 100 120.1 122.5 124.1 — 150 120.1 122.5 124.1 — -
[1] ARMBRUSTER W,HARDI J S,SUSLOV D,et al. Injector-driven flame dynamics in a high-pressure multi-element oxygen–hydrogen rocket thrust chamber[J]. Journal of Propulsion and Power,2019,35(3):632-644. doi: 10.2514/1.b37406 [2] LIEUWEN T C. Unsteady Combustor Physics[M]. Cam-bridge: Cambridge University Press, 2012. doi: 10.1017/cbo9781139059961 [3] OH S,JI H,KIM Y. FDF-based combustion instability analysis for stabilization effects of a slotted plate in a multiple flame combustor[J]. Aerospace Science and Tech-nology,2017,70:95-107. doi: 10.1016/j.ast.2017.07.045 [4] JI S X,WANG B. Modeling and analysis of triggering pulse to thermoacoustic instability in an end-burning-grain model solid rocket motor[J]. Aerospace Science and Technology,2019,95:105409. doi: 10.1016/j.ast.2019.105409 [5] LI L,ZHAO D. Prediction of stability behaviors of longitudinal and circumferential eigenmodes in a choked thermoacoustic combustor[J]. Aerospace Science and Tech-nology,2015,46:12-21. doi: 10.1016/j.ast.2015.06.024 [6] WANG Q,ZHANG Y,TANG H J,et al. Visualization of diffusion flame/vortex structure and dynamics under acou-stic excitation[J]. Combustion Science and Technology,2012,184(10-11):1445-1455. doi: 10.1080/00102202.2012.693419 [7] JANGI M,KOBAYASHI H. Droplet combustion in presence of airstream oscillation: mechanisms of enhancement and hysteresis of burning rate in microgravity at elevated pressure[J]. Combustion and Flame,2010,157(1):91-105. doi: 10.1016/j.combustflame.2009.06.004 [8] JANGI M,SHAW B,KOBAYASHI H. Thermal-drag and transition from quasi-steady to highly-unsteady combustion of a fuel droplet in the presence of upstream velocity oscillations[J]. Flow,Turbulence and Combustion,2009,84(1):97-123. doi: 10.1007/s10494-009-9230-2 [9] LI J,DUROX D,RICHECOEUR F,et al. Analysis of chemiluminescence,density and heat release rate fluctua-tions in acoustically perturbed laminar premixed flames[J]. Combustion and Flame,2015,162(10):3934-3945. doi: 10.1016/j.combustflame.2015.07.031 [10] JOCHER A,FOO K K,SUN Z W,et al. Impact of acoustic forcing on soot evolution and temperature in ethylene-air flames[J]. Proceedings of the Combustion Institute,2017,36(1):781-788. doi: 10.1016/j.proci.2016.08.025 [11] SCHULLER T,DUCRUIX S,DUROX D,et al. Modeling tools for the prediction of premixed flame transfer func-tions[J]. Proceedings of the Combustion Institute,2002,29(1):107-113. doi: 10.1016/S1540-7489(02)80018-9 [12] LIEUWEN T. Modeling premixed combustion-acoustic wave interactions: a review[J]. Journal of Propulsion and Power,2003,19(5):765-781. doi: 10.2514/2.6193 [13] FOO K K,SUN Z W,MEDWELL P R,et al. Experimental investigation of acoustic forcing on temperature, soot volume fraction and primary particle diameter in non-premixed laminar flames[J]. Combustion and Flame,2017,181:270-282. doi: 10.1016/j.combustflame.2017.04.002 [14] HASSAN M I,WU T W,SAITO K. A combination effect of reburn, post-flame air and acoustic excitation on NOx reduc-tion[J]. Fuel,2013,108:231-237. doi: 10.1016/j.fuel.2013.02.032 [15] FOO K K,SUN Z W,MEDWELL P R,et al. Influence of nozzle diameter on soot evolution in acoustically forced laminar non-premixed flames[J]. Combustion and Flame,2018,194:376-386. doi: 10.1016/j.combustflame.2018.05.026 [16] ZHENG L K,JI S D,ZHANG Y. Lifted and reattached behaviour of laminar premixed flame under external acoustic excitation[J]. Experimental Thermal and Fluid Science,2018,98:683-692. doi: 10.1016/j.expthermflusci.2018.07.013 [17] McKINNEY D J,DUNN-RANKIN D. Acoustically driven extinction in a droplet stream flame[J]. Combustion Science and Technology,2000,161(1):27-48. doi: 10.1080/00102200008935810 [18] BEISNER E,WIGGINS N D,YUE K B,et al. Acoustic flame suppression mechanics in a microgravity environment[J]. Microgravity Science and Technology,2015,27(3):141-144. doi: 10.1007/s12217-015-9422-4 [19] FRIEDMAN A N,STOLIAROV S I. Acoustic extinction of laminar line-flames[J]. Fire Safety Journal,2017,93:102-113. doi: 10.1016/j.firesaf.2017.09.002 [20] NIEGODAJEW P,ŁUKASIAK K,RADOMIAK H,et al. Application of acoustic oscillations in quenching of gas burner flame[J]. Combustion and Flame,2018,194:245-249. doi: 10.1016/j.combustflame.2018.05.007 [21] 阚瑞峰,夏晖晖,许振宇,等. 激光吸收光谱流场诊断技术应用研究与进展[J]. 中国激光,2018,45(9):0911005. doi: 10.3788/CJL201845.0911005KAN R F,XIA H H,XU Z Y,et al. Research and progress of flow field diagnosis based on laser absorption spectro-scopy[J]. Chinese Journal of Lasers,2018,45(9):0911005. doi: 10.3788/CJL201845.0911005 [22] ALDÉN M,BOOD J,LI Z S,et al. Visualization and understanding of combustion processes using spatially and temporally resolved laser diagnostic techniques[J]. Pro-ceedings of the Combustion Institute,2011,33(1):69-97. doi: 10.1016/j.proci.2010.09.004 [23] SJÖHOLM J,ROSELL J,LI B,et al. Simultaneous visualization of OH,CH,CH2O and toluene PLIF in a methane jet flame with varying degrees of turbulence[J]. Proceedings of the Combustion Institute,2013,34(1):1475-1482. doi: 10.1016/j.proci.2012.05.037 [24] HARRINGTON J E,SMYTH K C. Laser-induced fluore-scence measurements of formaldehyde in a methane/air diffusion flame[J]. Chemical Physics Letters,1993,202(3-4):196-202. doi: 10.1016/0009-2614(93)85265-P [25] LOZANO A,YIP B,HANSON R K. Acetone: a tracer for concentration measurements in gaseous flows by planar laser-induced fluorescence[J]. Experiments in Fluids,1992,13(6):369-376. doi: 10.1007/BF00223244 [26] THURBER M C,GRISCH F,KIRBY B J,et al. Measu-rements and modeling of acetone laser-induced fluorescence with implications for temperature-imaging diagnostics[J]. Applied Optics,1998,37(21):4963-4978. doi: 10.1364/ao.37.004963 [27] THURBER M C,HANSON R K. Pressure and composition dependences of acetone laser-induced fluorescence with excitation at 248,266,and 308 nm[J]. Applied Physics B,1999,69(3):229-240. doi: 10.1007/s003400050799 [28] ROTHAMER D A,SNYDER J A,HANSON R K,et al. Optimization of a tracer-based PLIF diagnostic for simul-taneous imaging of EGR and temperature in IC engines[J]. Applied Physics B,2010,99(1-2):371-384. doi: 10.1007/s00340-009-3815-2 [29] LI Z S,LI B,SUN Z W,et al. Turbulence and combustion interaction: high resolution local flame front structure visualization using simultaneous single-shot PLIF imaging of CH,OH,and CH2O in a piloted premixed jet flame[J]. Combustion and Flame,2010,157(6):1087-1096. doi: 10.1016/j.combustflame.2010.02.017 [30] ZHANG M,WANG J H,XIE Y L,et al. Flame front structure and burning velocity of turbulent premixed CH4/H2/air flames[J]. International Journal of Hydrogen Energy,2013,38(26):11421-11428. doi: 10.1016/j.ijhydene.2013.05.051 [31] ZHANG M,WANG J H,WU J,et al. Flame front structure of turbulent premixed flames of syngas oxyfuel mixtures[J]. International Journal of Hydrogen Energy,2014,39(10):5176-5185. doi: 10.1016/j.ijhydene.2014.01.038 [32] WANG J H,NIE Y H,ZHANG W J,et al. Network topology of turbulent premixed Bunsen flame at elevated pressure and turbulence intensity[J]. Aerospace Science and Technology,2019,94:105361. doi: 10.1016/j.ast.2019.105361