超声速条件下亚毫米液滴的变形破碎模态

Deformation and fracture patterns of sub-millimeter droplets under supersonic conditions

以超声速气流中液滴变形破碎行为为研究内容,对水平激波管中承受激波冲击的亚毫米水液滴(0.44~1.09 mm)变形破碎过程进行了观测,实验激波马赫数范围为1.07~2.11。利用纹影法,结合高分辨率高速相机对不同破碎模态下液滴的变形破碎特征进行了记录,得到了袋状、多模态、剪切和爆炸式等破碎模式下的液滴纹影图像,分析了液滴运动参数的时空关系。得出了液滴变形阶段,液滴无量纲横向变形宽度以及液滴无量纲迎风面位移随无量纲时间的变化发展规律,并且得出在液滴初始直径相同时,不同液滴破碎模式的无量纲最大横向变形宽度的变化,其中袋状、多模态、剪切破碎模式的无量纲横向最大变形宽度均在1.15~1.61范围内变化,爆炸式破碎模式的无量纲横向最大变形宽度均在0.21~0.68范围内变化。

Based on the deformation behavior and mechanism of droplet deformation under supersonic conditions, the deformation and fracture process of sub-millimeter water droplets(0.44-1.09 mm) under shock was observed in a horizontal shock tube. The shock Mach number range was 1.07-2.11. Using the schlieren method, in combination with the high-resolution high-speed camera to record the deformation and fracture characteristics of droplets under different crush modes, the droplet streak images of the bag-shaped crushing, multi-modal crushing, shearing and explosive crushing modes were obtained. The droplet pattern image was analyzed on the temporal and spatial relationship of the motion parameters of the droplet. The development law of the droplet deformation stage with different diameters, the dimensionless lateral deformation width of the droplet and the dimensionless windward surface displacement of the droplet with the dimensionless time were obtained. And the maximum dimensionless lateral deformation was obtained with different droplet breaking modes when the initial diameter of the droplet was the same. As for the width changes, the dimensionless transverse maximum deformation widths variation range of the bag-shaped, multi-modal and shear crushing modes was 1.15-1.61, and the dimensionless maximum transverse deformation widths variation range of the explosive crushing mode was 0.21-0.68.