Instabilities of a liquid column jet in a surrounding gas flowing through a coaxial cylindrical sheath
Instabilities of a liquid column jet in a surrounding gas flowing through a coaxial cylindrical sheath
复制标题
流过同轴圆柱形护套的周围气体中液柱射流的不稳定性
DOI：
10.1088/1873-7005/ab9a9e
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发表时间：
2020
影响因子：
1.5
通讯作者：
Yoshinaga Takao
中科院分区：
文献类型：
--
作者：
Y. Sugitani;K. Tsujimoto;T. Shakouchi;T. Ando;Yoshinaga Takao
本文解析地研究了粘性液柱射流流经同轴圆柱形护套时，在无粘静止环境气体中的不稳定性和破碎现象。在长波近似下，推导了射流和周围气体的轴对称非线性演化方程，并在空间周期边界条件下进行了数值求解。通过与精确三维不稳定性的比较，考察了该近似在线性区域内的有效性和局限性。非线性分析表明，存在三种破碎模式：表面张力不稳定性占主导地位的Rayleigh模式，其破裂是由收缩引起的；第一种风致模式，由于空气动力不稳定性的增加而产生由螺纹连接的气泡；第二种风致模式，喷流表面变形成尖状，不发生收缩，液滴从尖端产生。在不同雷诺数和密度比下，在韦伯数和鞘层半径的参数空间中考察了这些模式的存在区域。
In this paper, instabilities and breakup phenomena of a viscous liquid column jet in an inviscid stationary surrounding gas are analytically investigated, when the jet flows through a coaxial cylindrical sheath. Under a long wave approximation, axisymmetric non-linear evolution equations of the jet and surrounding gas are derived and numerically solved under a spatially periodic boundary condition. Validity and limitation of the approximation are examined in the linear regime in comparison with exact three-dimensional instabilities. It is shown in the non-linear analysis that there exist three types of breakup modes: the Rayleigh mode in which the surface tension instability is dominant and the breakup is caused by pinching, the first wind-induced mode in which blobs connected by threads are produced by increased aerodynamic instability and the second wind-induced mode in which the jet surface deforms to be spiked like a cusp without pinching and droplets are to be produced from a tip of the cusp. The existing regions of these modes are examined in the parameter space of the Weber number and the sheath radius for different Reynolds numbers and density ratios.