单个上升空泡撞击顶部壁面的变形和回弹特性研究

Deformation and Rebound Characteristics of Single Rising Bubble Impacting against Top Wall

附着在固体壁面的空泡具有减阻的作用,空泡的动力学特性决定其能否实现减阻效果及减阻的程度。从雷诺数和材料表面性质的角度,对单个空泡与壁面相互作用过程中的动力学特性进行研究,通过改变空泡速度、黏度、大小以及壁面表面接触角来探讨雷诺数和材料表面性质对空泡的影响。结果表明,在黏度相同的情况下,空泡最大变形程度随雷诺数的增大而增加,空泡对壁面的冲击力则是随空泡体积的增大而增强。此外,液体黏度的增大会使空泡最大变形程度加强,但却能更快达到稳定,而接近壁面的速度增加以及空泡体积的增大会使得空泡变形程度加剧,且延长空泡达到稳定的时间。材料表面性质方面,空泡的变形程度随固体表面接触角的增大而减小,表面达到超疏水状态,空泡最大变形程度大幅度降低。

Bubble lying on the wall can reduce resistance between liquid and wall, which is related to the dynamic characteristics of bubble closing to a wall. In terms of Reynolds number and surface property of material, property of a single bubble interacting with a wall is researched, and analyzing the effect of Reynolds number and surface property on the dynamic characteristics of bubble by changing the speed, viscosity, volume of bubble and the contact angle of surface. The results show that the lager Reynolds number could lead to a more serious deformation of bubble with the same viscosity. Impact between bubble and wall will become stronger as the increase of volume of bubble. Another, the maximum deformation of bubble will increase with the raise of viscosity, while it could reach balance faster. Except that, both of higher speed of bubble closed to wall and lager volume could lead to a more serious deformation and take more time to reach balance. The deformation of bubble decreases with contact angle increasing. The deformation of bubble decreases significantly until surface reaching the superhydrophobic state.