不同环境压力下幂律流体撞击射流破碎特性
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摘要
基于自行搭建的射流系统和定容弹系统,采用高速摄影技术,获得了高环境压力下幂律流体对称撞击式射流的喷雾形貌,提取了射流特征参数破碎长度L与表面波长λ,研究了环境参数(环境压力)、射流参数(韦伯数We)、结构参数(喷孔直径)与物性参数(流体黏度)对射流破碎的影响.结果表明:幂律流体对称撞击式射流共有封闭边界模式、开边界模式、无边界模式、弓形液线模式和完全发展模式共5种破碎模式;在大气环境压力下,L随着We的增加呈"双峰"模式变化;而在有环境压力的情况下,L与We则呈"单峰"模式变化;与大气环境压力相比,高环境压力更有利于幂律流体对称撞击式射流破碎;而喷孔直径与流体黏度的增大均不利于撞击式射流破碎.提出了预测幂律流体对称撞击射流破碎表面波长的破碎模型.
Experimental observations and analysis on the fluid sheet formed by symmetric impinging jet injectors of power law fluid under high ambient pressure were presented.Constant volume chamber system and high-speed photography technology were used to obtain breakup regimes and spray characteristics.The characteristic parameters such as breakup length L and wave length λ were extracted from the photograph.This paper investigated the environmental parameter(ambient pressure),jet parameter(Weber number),geometry parameter(orifice diameter)and physical parameter(fluid viscosity)on the atomization behaviors of liquid sheets.It is found that the spray regimes could be qualitatively categorized into five types:closed-rim,open-rim,rimless,bow-shaped ligaments and fully developed regimes.In the open space,the L increases with the We in ‘double peak' mode.While in the case of situation with ambient pressure,the L and the We are in ‘single peak' mode.Compared with the open space conditions,the high ambient pressure conditions are more favorable to the power law fluid symmetric impact jet breakup.And the increase of orifice diameter and fluid viscosity all inhibit the impingement jet from breakup.An empirical relation for predicting the surface wave length is proposed.
Experimental observations and analysis on the fluid sheet formed by symmetric impinging jet injectors of power law fluid under high ambient pressure were presented.Constant volume chamber system and high-speed photography technology were used to obtain breakup regimes and spray characteristics.The characteristic parameters such as breakup length L and wave length λ were extracted from the photograph.This paper investigated the environmental parameter(ambient pressure),jet parameter(Weber number),geometry parameter(orifice diameter)and physical parameter(fluid viscosity)on the atomization behaviors of liquid sheets.It is found that the spray regimes could be qualitatively categorized into five types:closed-rim,open-rim,rimless,bow-shaped ligaments and fully developed regimes.In the open space,the L increases with the We in ‘double peak' mode.While in the case of situation with ambient pressure,the L and the We are in ‘single peak' mode.Compared with the open space conditions,the high ambient pressure conditions are more favorable to the power law fluid symmetric impact jet breakup.And the increase of orifice diameter and fluid viscosity all inhibit the impingement jet from breakup.An empirical relation for predicting the surface wave length is proposed.
引文
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[2]Lai W H,Huang W,Jiang T L.Characteristic study on the like-doublet impinging jets atomization[J].Atomization&Sprays,1999,9(3):277-289.
[3]Li R,Ashgriz N.Characteristics of liquid sheets formed by two impinging jets[J].Physics of Fluids,2006,18(8):4-16.
[4]Jung K,Khil T,Yoon Y,et al.The breakup characteristics of liquid sheet formed by like-doublet injectors[C]//38th AIAA Joint Propulsion Conference and Exhibit,Indianapolis,IN,USA,2002,AIAA-2002-4177.
[5]伊吉明,白富强,常青,等.撞击式射流速度特性及液滴粒度特性的试验[J].内燃机学报,2013,31(6):519-524.
[6]Chen X,Ma D,Yang V,et al.High-fidelity simulations of impinging jet atomization[J].Atomization and Sprays,2013,23(12):1070-1101.
[7]Von K J,Alberio F,Ciezki H K.Spray and combustion characteristics of aluminized gelled fuels with an impinging jet injector[J].Aerospace Science and Technology,2007,11(1):77-83.
[8]Fu Q,Yang L,Cui K,et al.Effects of orifice geometry on gelled propellants sprayed from impinging-jet injectors[J].Journal of Propulsion and Power,2014,30(4):1112-1117.
[9]Bai F,Diao H,Zhang M,et al.Breakup characteristics of power-law liquid sheets formed by two impinging jets[J].Fluid Dynamics Research,2014,46(5):6-21.
[10]Fu Q,Duan R,Yang L.Spray of gelled propellants from an impinging-jet injector under different temperatures[J].Aerospace Science and Technology,2014,39(1):552-558.
[11]Yang L,Fu Q,Qu Y,et al.Breakup of a power-law liquid sheet formed by an impinging jet injector[J].International Journal of Multiphase Flow,2012,39(1):37-44.
[12]Lee E J,Oh S Y,Kim H Y,et al.Measuring air core characteristics of a pressure-swirl atomizer via a transparent acrylic nozzle at various Reynolds numbers[J].Experimental Thermal and Fluid Science,2010,34(8):1475-1483.
[13]Mead-Hunter R,King A J C,Mullins B J.Plateau rayleigh instability simulation[J].Langmuir,2012,28(17):6731-6735.
[14]Lee I,Koo J.Break-up characteristics of gelled propellant simulants with various gelling agent contents[J].Journal of Thermal Science,2010,19(6):545-552.
[15]Squire H B.Investigation of the instability of a moving liquid film[J].British Journal of Applied Physics,1953,4(6):167-169.
[16]韩占忠,王国玉.工程流体力学基础[M].北京:北京理工大学出版社,2016.
[17]Lourakis M,Argyros A.The design and implementation of a generic sparse bundle adjustment software package based on the Levenberg-Marquardt algorithm[R].Technical Report 340,Institute of Computer ScienceFORTH,Heraklion,Crete,Greece,2004.