李经警1,张勃1,张纳如1,吉洪湖1,叶留增2,许羚2.基于大涡模拟的圆转矩喷管尾喷流强化掺混机理研究[J].航空发动机,2018,44(2):27-34
基于大涡模拟的圆转矩喷管尾喷流强化掺混机理研究
Research and Application of Design Method of MBD Technique with Simplified Dimension Annotation
  
DOI:
中文关键词:  大涡模拟  2 元喷管  拟序结构  雷诺应力  强化掺混
英文关键词:LES  two-dimensional nozzle  coherent structure  Reynolds shear stress  mixing enhancement
基金项目:航空科学基金(20152752034)资助
作者单位E-mail
李经警1,张勃1,张纳如1,吉洪湖1,叶留增2,许羚2 1.南京航空航天大学能源与动力学院南京2100162.中国航发沈阳发动机研究所沈阳110015 2425777670@qq.com 
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中文摘要:
      为揭示2 元圆转矩喷管尾喷流强化掺混的内在机制,应用大涡模拟(LES)方程对2 种相同进、出口直径的喷管模型(轴对 称、2 元圆转矩)在Ma=0.8、高雷诺数(2×105)条件下进行了数值模拟计算。结果表明:与轴对称喷管相比,圆转矩喷管射流掺混效 应增强,速度衰减快,核心区长度和高温区域面积减小。同时尾喷流拟序结构变化说明:2 种喷管主要拟序结构均包含涡环、涡辫、发 卡涡、螺旋涡等相似结构;但圆转矩喷管在射流近场诱导出的涡旋更丰富,边角剪切涡发展更快,形成明显的CVP 结构,导致其射流 柱失稳时刻提前、距离缩短;同时,喷管形式的改变使得射流剪切层内雷诺应力增大,速度脉动增强。拟序结构发展及雷诺剪切应力 变化说明在射流流场中涡旋发展耗散速度增大、速度边界层脉动增强、射流柱易失稳是导致射流掺混增强的本质因素,为异形喷管 的强化掺混机理提供了依据。
英文摘要:
      In order to reveal the internal mechanism of mixing enhancement of 2-D circle-rectangular transition nozzle, the numerical simulation by the Large Eddy Simulation (LES) equation of mixing characteristics of jet and environment were studied at two nozzle model with the same inlet and outlet diameters, which were symmetrical and circle-rectangular transition nozzle with low Mach number 渊Ma=0.8冤 and high Reynolds number渊2伊105冤. The results show that the circle-rectangular transition nozzle jet has the strengthening mixing effect, the faster velocity decay rate, the reduction potential core -length and the shrinking area of high temperature, comparing with the axial symmetric nozzle. The variations of coherent structure of the tail jet flow show that the main structures of two kinds of nozzle are vortex ring, vortex braid, Hairpin Vortex, spiral vortex and so on, but the circle-rectangular transition nozzle model produces a wide variety of vortexes in the near field of jet, the shear vortex develops faster and forms an obvious CVP , which causes the instability point of the jet column earlier and closer to the exit. In addition, the change of nozzle form makes the Reynolds stress in the jet shear layer increase, the velocity fluctuation is more intense and the mixing is enhanced. In the jet flow field, the rapider development of vortex, the increase of vortex dissipation rate and the increase of velocity boundary layer fluctuation are the essential factors leading to mixing enhancement, which also provide the basis for strengthening mixing mechanism of profiled nozzle.
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