POD analysis of the dynamic structures of a low swirl number precessing jet
-
摘要: 利用粒子图像测速技术（PIV）对雷诺数Re = 4.5×104的低旋流数旋进射流流场进行了实验测量，并利用本征正交分解（POD）方法对测得的流场进行分解，提取流场中含能大尺度结构。针对3种不同旋流数（S = 0、 0.26和0.41），对比分析了POD分解得到的空间模态以及用POD模态重构后的脉动速度场的变化规律。POD分析得到的结果表明：旋进导致流体交替地从腔体一侧沿着壁面流出，从另一侧流入；旋进刚发生时，上游剪切层内的旋涡结构尚未完全破坏，它们会一直向下游发展直至旋进起始点附近后，开始随着主流一起偏转，而下游剪切层内的大尺度结构被完全破坏；随着旋流数的增加，旋进以及射流的自身振荡被加强，从而导致流场结构更加复杂、大尺度旋涡结构被破坏。Abstract: The flow field of a low swirl number precessing jet at Reynolds number Re = 4.5×104 is measured using particle image velocimetry （PIV） and the dynamics of the large-scale flow structures are examined further using the proper orthogonal decomposition（POD） analysis. The spatial modes obtained by POD and the fluctuating velocity field obtained by POD reconstruction at three swirl numbers, i.e., S = 0, 0.26 and 0.41, are compared and analyzed. The POD results show that the precession induces an alternating flow, switching between outflow from one side of the chamber along the chamber wall and inflow from another side. When the precession occurs, the vortex structures in the upstream shear layers have not broken down completely. They will develop downstream until approaching the starting point of the precession and then deflect with the mainstream. However, the large-scale structures in the downstream shear layers are completely destroyed. As the swirl number increases, the region affected by the precession moves upstream, and the orderly vortex structures in the shear layers break down.
-
Keywords:
- POD analysis /
- low swirl number /
- precessing jet /
- dynamic structures
-
-
![]()
图 1 实验装置示意图和几何尺寸
Fig. 1 Schematic diagram of the experimental setup and geometric sizes
![]()
图 3 旋流数 S = 0 时区域Ⅰ内的前六阶模态
Fig. 3 The first six POD modes in zone Ⅰ at swirl number S = 0
![]()
图 4 原始流场（a）-（d）及重构脉动速度场（e）-（h）云图（旋流数 S = 0，区域Ⅰ）
Fig. 4 Contour plot of (a)-(d) the original field and (e)-(h) the recon-structed fluctuating velocity field (swirl number S = 0, zone Ⅰ)
![]()
图 5 旋流数 S = 0 时区域Ⅱ内的前六阶模态
Fig. 5 The first six POD modes in zone Ⅱ at swirl number S = 0
![]()
图 6 原始流场（a）-（d）及重构脉动速度场（e）-（h）云图（旋流数 S = 0，区域Ⅱ）
Fig. 6 Contour plot of (a)-(d) the original field and (e)-(h) the recon-structed fluctuating velocity field (swirl number S = 0, zone Ⅱ)
![]()
图 7 旋流数 S = 0.26 时区域Ⅰ内的前六阶模态
Fig. 7 The first six POD modes in zone Ⅰ at swirl number S = 0.26
![]()
图 8 原始流场（a）-（d）及重构脉动速度场（e）-（h）云图（旋流数 S = 0.26，区域Ⅰ）
Fig. 8 Contour plot of (a)-(d) the original field and (e)-(h) the recon-structed fluctuating velocity field ( S = 0.26, zone Ⅰ)
![]()
图 9 旋流数 S = 0.26 时区域Ⅱ内的前六阶模态
Fig. 9 The first six POD modes in zone Ⅱ at swirl number S = 0.26
![]()
图 10 原始流场（a）-（d）及重构脉动速度场（e）-（h）云图（旋流数 S = 0.26，区域Ⅱ）
Fig. 10 Contour plot of (a)-(d) the original field and (e)-(h) the recon-structed fluctuating velocity field ( S = 0.26, zone Ⅱ)
![]()
图 11 旋流数 S = 0.41 时区域Ⅰ内的前六阶模态
Fig. 11 The first six POD modes in zone Ⅰ at swirl number S = 0.41
![]()
图 12 原始流场（a）-（d）及重构脉动速度场（e）-（h）云图（旋流数 S = 0.41，区域Ⅰ）
Fig. 12 Contour plot of (a)-(d) the original field and (e)-(h) the recon-structed fluctuating velocity field ( S = 0.41, zone Ⅰ)
![]()
图 13 旋流数 S = 0.41时区域Ⅱ内的前六阶模态
Fig. 13 The first six POD modes in zone Ⅱ at swirl number S = 0.41
-
[1] NATHAN G J, MANIAS C G. The role of process and flame interaction in reducing NOx emissions[C]//Proceedings of the Institute of Energy's Second International Conference on Combustion & Emissions Control. 1995. doi: 10.1016/b978-0-902597-49-5.50032-9
[2] NEWBOLD G J R,NATHAN G J,NOBES D S,et al. Measurement and prediction of NOx emissions from unconfined propane flames from turbulent-jet, bluff-body, swirl, and precessing jet burners[J]. Proceedings of the Combustion Institute,2000,28(1):481-487. doi: 10.1016/S0082-0784(00)80246-5
[3] DENG Y B,WU H W,SU F M. Combustion and exhaust emission characteristics of low swirl injector[J]. Applied Thermal Engineer-ing,2017,110:171-180. doi: 10.1016/j.applthermaleng.2016.08.169
[4] COLORADO A,MCDONELL V. Emissions and stability performance of a low-swirl burner operated on simulated biogas fuels in a boiler environment[J]. Applied Thermal Engineering,2018,130:1507-1519. doi: 10.1016/j.applthermaleng.2017.11.047
[5] TONG Y H,YU S B,LIU X,et al. Experimental study on dynamics of a confined low swirl partially premixed methane-hydrogen-air flame[J]. International Journal of Hydrogen Energy,2017,42(44):27400-27415. doi: 10.1016/j.ijhydene.2017.09.066
[6] NATHAN G J,HILL S J,LUXTON R E. An axisymmetric ‘fluidic’ nozzle to generate jet precession[J]. Journal of Fluid Mechanics,1998,370:347-380. doi: 10.1017/s002211209800202x
[7] LUXTON R E, NATHAN G J. Mixing fluids: Australian, PCT/AU88/0014[P]. 1987.
[8] NATHAN G J,MI J,ALWAHABI Z T,et al. Impacts of a jet's exit flow pattern on mixing and combustion performance[J]. Progress in Energy and Combustion Science,2006,32(5-6):496-538. doi: 10.1016/j.pecs.2006.07.002
[9] MADEJ A M,BABAZADEH H,NOBES D S. The effect of chamber length and Reynolds number on jet precession[J]. Experiments in Fluids,2011,51(6):1623-1643. doi: 10.1007/s00348-011-1177-0
[10] WONG C Y,LANSPEARY P V,NATHAN G J,et al. Phase-averaged velocity in a fluidic precessing jet nozzle and in its near external field[J]. Experimental Thermal and Fluid Science,2003,27(5):515-524. doi: 10.1016/S0894-1777(02)00265-0
[11] CAFIERO G,CEGLIA G,DISCETTI S,et al. On the three-dimensional precessing jet flow past a sudden expansion[J]. Experi-ments in Fluids,2014,55(2):1-13. doi: 10.1007/s00348-014-1677-9
[12] CEGLIA G,CAFIERO G,ASTARITA T. Experimental investigation on the three-dimensional organization of the flow structures in pre-cessing jets by tomographic PIV[J]. Experimental Thermal and Fluid Science,2017,89:166-180. doi: 10.1016/j.expthermflusci.2017.08.008
[13] CHAN C K, LAU K S, CHIN W K, et al. Freely propagating open premixed turbulent flames stabilized by swirl[C]//Proc of the Sym-posium (International) on Combustion. 1992. doi: 10.1016/S0082-0784(06)80065-2.
[14] CHENG R K. Velocity and scalar characteristics of premixed turbulent flames stabilized by weak swirl[J]. Combustion and Flame,1995,101(1-2):1-14. doi: 10.1016/0010-2180(94)00196-Y
[15] DELLENBACK P A,METZGER D E,NEITZEL G P. Measurements in turbulent swirling flow through an abrupt axisymmetric expan-sion[J]. AIAA Journal,1988,26(6):669-681. doi: 10.2514/3.9952
[16] MARKOVICH D M,ABDURAKIPOV S S,CHIKISHEV L M,et al. Comparative analysis of low- and high-swirl confined flames and jets by proper orthogonal and dynamic mode decompositions[J]. Physics of Fluids,2014,26(6):2893-2900. doi: 10.1063/1.4884915
[17] 付豪,何创新,刘应征. 低旋流数旋进射流流动特性的PIV实验研究[J]. 实验流体力学,2021,35(3):39-45. DOI: 10.11729/syltlx20200129 FU H,HE C X,LIU Y Z. PIV experimental study on flow characteri-stics of a low swirl number precessing jet[J]. Journal of Experi-ments in Fluid Mechanics,2021,35(3):39-45. doi: 10.11729/syltlx20200129
[18] HE C X,GAN L,LIU Y Z. The formation and evolution of turbulent swirling vortex rings generated by axial swirlers[J]. Flow, Turbulence and Combustion,2020,104(4):795-816. doi: 10.1007/s10494-019-00076-2
[19] SIROVICH L. Turbulence and the dynamics of coherent structures. II. Symmetries and transformations[J]. Quarterly of Applied Mathe-matics,1987,45(3):573-582. doi: 10.1090/qam/910463
[20] SEMERARO O,BELLANI G,LUNDELL F. Analysis of time-resolved PIV measurements of a confined turbulent jet using POD and Koopman modes[J]. Experiments in Fluids,2012,53(5):1203-1220. doi: 10.1007/s00348-012-1354-9
下载:
计量
- 文章访问数: 1204
- HTML全文浏览量: 443
- PDF下载量: 140
