The Reynolds-averaged Navier–Stokes (RANS), large eddy simulation (LES), and coupled level set-volume of fluid (CLSVOF) methods were used to numerically investigate the breakup characteristics of three-dimensional unsteady circular jets. The jet breakup lengths and initial amplitudes of the surface waves of the jets from nozzles with different geometries were measured in a high-speed photography (HSP) experiment. The numerical model showed the formation, development, and variation of the jet flow structure. The circumferential and sinusoidal waves on the jet surface were captured by a high-speed camera, and the entrainment effect of the jet was studied with LES. The time-averaged velocity distribution fields were clarified with LES; the breakup of the liquid band structure and formation of droplets led to irregular changes in the droplet velocities, which indicates that the LES of the jet breakup was close to the actual situation. The relative errors between the simulation and experimental values for the breakup length and initial amplitude of the surface waves of the jet were less than 10%, which confirms that LES and CLSVOF can accurately and feasibly extract the details of circular jet breakup characteristics under intermediate- and low-pressure conditions.

中文翻译：

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不同喷嘴几何形状圆形射流的三维流动破碎特性

雷诺平均纳维-斯托克斯 (RANS)、大涡模拟 (LES) 和耦合水平集流体体积 (CLSVOF) 方法用于数值研究三维非定常圆形射流的破碎特性。在高速摄影 (HSP) 实验中测量了来自具有不同几何形状的喷嘴的射流的表面波的射流破裂长度和初始振幅。数值模型显示了射流结构的形成、发展和变化。高速相机捕捉射流表面的圆周波和正弦波，并用 LES 研究了射流的夹带效应。时均速度分布场用LES澄清；液带结构的分裂和液滴的形成导致液滴速度的不规则变化，这表明射流分裂的LES接近实际情况。射流表面波破裂长度和初始振幅的模拟值与实验值的相对误差均小于10%，证明LES和CLSVOF能够准确、可行地提取出中等强度下圆形射流破裂特征的细节。和低压条件。