In this article the emphasis was given to the discussion of the effects of diameter ratio and swirling on instability character for the gas/liquid coaxial jet used by Liao, et al.[1], The results indicate that the fin...In this article the emphasis was given to the discussion of the effects of diameter ratio and swirling on instability character for the gas/liquid coaxial jet used by Liao, et al.[1], The results indicate that the finite diameter ratio markedly increases the maximum growth rate, the most unstable wavenumber, as well as the cutoff wavenumber. It implies that the finite diameter ratio will lead to the liquid jet breakup length shorter and the liquid drop size smaller. The effect of the swirling jets is much more complex： for the axisymmetric perturbation mode, the swirling enhances the flow stability, for helical perturbation, the dominant instability mode occurs at n〈0. And it is found that in long wave region there exists a new kind of instability modes at n=l that was not mentioned in Liao et al.＇s article. For this new mode, there appears a dominated swirling ratio at which the flow has the maximum growth rate.展开更多
在增压条件下对一种旋流式气液同轴喷油器的雾化特性进行研究。在不同的环境背压条件下,采用PDPA测量距离喷口处70mm的液雾分布,研究了环境背压、气液相对速度、以及燃油流速对索特平均直径(Sauter mean diameter,SMD)的影响规律。结果...在增压条件下对一种旋流式气液同轴喷油器的雾化特性进行研究。在不同的环境背压条件下,采用PDPA测量距离喷口处70mm的液雾分布,研究了环境背压、气液相对速度、以及燃油流速对索特平均直径(Sauter mean diameter,SMD)的影响规律。结果表明:当保证燃油流速一定、气液相对速度一定的条件下,SMD随环境背压的增大而减小;当环境背压及燃油流速一定的条件下,SMD随气液相对速度的增大而减小;当保证雾化空气压力以及环境背压一定的条件下,燃油流速对SMD的影响规律存在一个拐点,随着燃油流速的增加,SMD先增加后减小,在文中的试验条件下,燃油流速拐点值约为9.91m/s。根据试验数据整理出SMD与环境背压、气液相对速度及燃油流速的拟合公式。展开更多
高温燃气流风洞的加热段喷注面板由数百个气液同轴离心喷嘴组成,各喷嘴间存在强烈的喷雾干涉现象,导致喷雾场相互耦合。为探究气体中心式气液同轴离心喷嘴喷雾的耦合对雾化特性及流场均匀性的影响,通过实验和仿真的方式研究了不同气液...高温燃气流风洞的加热段喷注面板由数百个气液同轴离心喷嘴组成,各喷嘴间存在强烈的喷雾干涉现象,导致喷雾场相互耦合。为探究气体中心式气液同轴离心喷嘴喷雾的耦合对雾化特性及流场均匀性的影响,通过实验和仿真的方式研究了不同气液比对多喷嘴雾化特性的影响,以及喷嘴间距和喷嘴数目对喷雾流强分布的影响。设计安装多喷嘴的喷注器,搭建喷雾检测实验台,采用高速相机拍摄喷雾图像,采用马尔文激光粒度仪测量喷雾场中的液滴尺寸;并设计了流强测量系统,以测量喷雾场的流强分布。采用流体体积法(Volume of Fluid,VOF)和网格自适应技术(Adaptive Mesh Refinement,AMR)对多喷嘴的耦合喷雾场进行模拟。结果表明,仿真结果与实验测得的流量分布基本吻合;在液体流量较大的工况下,喷雾锥角基本稳定,粒径大小受液膜撞击破碎和液滴撞击聚合双重作用的影响;随着喷嘴间距的增加,喷雾分布的不均匀性增强;并且当存在3个及以上喷嘴时,喷雾场两两相互干涉,在喷雾耦合区域出现流强高峰。展开更多
基金supported by the National Natural Science Foundation of China (Grant No. 10172082).
文摘In this article the emphasis was given to the discussion of the effects of diameter ratio and swirling on instability character for the gas/liquid coaxial jet used by Liao, et al.[1], The results indicate that the finite diameter ratio markedly increases the maximum growth rate, the most unstable wavenumber, as well as the cutoff wavenumber. It implies that the finite diameter ratio will lead to the liquid jet breakup length shorter and the liquid drop size smaller. The effect of the swirling jets is much more complex： for the axisymmetric perturbation mode, the swirling enhances the flow stability, for helical perturbation, the dominant instability mode occurs at n〈0. And it is found that in long wave region there exists a new kind of instability modes at n=l that was not mentioned in Liao et al.＇s article. For this new mode, there appears a dominated swirling ratio at which the flow has the maximum growth rate.
文摘在增压条件下对一种旋流式气液同轴喷油器的雾化特性进行研究。在不同的环境背压条件下,采用PDPA测量距离喷口处70mm的液雾分布,研究了环境背压、气液相对速度、以及燃油流速对索特平均直径(Sauter mean diameter,SMD)的影响规律。结果表明:当保证燃油流速一定、气液相对速度一定的条件下,SMD随环境背压的增大而减小;当环境背压及燃油流速一定的条件下,SMD随气液相对速度的增大而减小;当保证雾化空气压力以及环境背压一定的条件下,燃油流速对SMD的影响规律存在一个拐点,随着燃油流速的增加,SMD先增加后减小,在文中的试验条件下,燃油流速拐点值约为9.91m/s。根据试验数据整理出SMD与环境背压、气液相对速度及燃油流速的拟合公式。
文摘高温燃气流风洞的加热段喷注面板由数百个气液同轴离心喷嘴组成,各喷嘴间存在强烈的喷雾干涉现象,导致喷雾场相互耦合。为探究气体中心式气液同轴离心喷嘴喷雾的耦合对雾化特性及流场均匀性的影响,通过实验和仿真的方式研究了不同气液比对多喷嘴雾化特性的影响,以及喷嘴间距和喷嘴数目对喷雾流强分布的影响。设计安装多喷嘴的喷注器,搭建喷雾检测实验台,采用高速相机拍摄喷雾图像,采用马尔文激光粒度仪测量喷雾场中的液滴尺寸;并设计了流强测量系统,以测量喷雾场的流强分布。采用流体体积法(Volume of Fluid,VOF)和网格自适应技术(Adaptive Mesh Refinement,AMR)对多喷嘴的耦合喷雾场进行模拟。结果表明,仿真结果与实验测得的流量分布基本吻合;在液体流量较大的工况下,喷雾锥角基本稳定,粒径大小受液膜撞击破碎和液滴撞击聚合双重作用的影响;随着喷嘴间距的增加,喷雾分布的不均匀性增强;并且当存在3个及以上喷嘴时,喷雾场两两相互干涉,在喷雾耦合区域出现流强高峰。
