关键词: 液滴撞击, 旋转壁面, 黏性, 转速, 偏心撞击, 铺展因子

Abstract:

Droplet impact on the rotating wall widely exists in the engineering field， such as rain ingestion and ice accretion occurring on aircraft engines， which will lead to efficiency loss and even safety problems. Therefore， it is of great significance to study the impact of liquid droplets on the rotating wall. An experimental set-up of droplet impacting on a rotating disc is built and experiments are conducted and recorded with a high-speed camera. The effects of the rotating speed and viscosity on the droplet spreading after off-axis impact are studied while the droplet size， impact velocity， surface tension and impact position remain unchanged. The evolution of droplet diameter data along the radial and tangential directions was quantitatively obtained by post-processing the recoded images. The experimental results show that the radial-tangential spreading dynamic follows four different regimes with the rotational Bond number and rotational Reynolds number： impact inertia force-adhesion force， impact inertia force-adhesion force/viscous force transition， impact inertia force/centrifugal force transition-adhesion force， and impact inertia force-viscous force. In the impact inertial force dominant regime for the radial spreading， the maximum radial spreading factor decreases with the Ohnesorge number and the rotational Bond number， and the radial spreading factor evolves with the dimensionless time t/（Oh·T） by a -1/3 pow-law. In the tangential adhesion force dominant regime， the tangential spreading rate of droplets exhibits a 2/3 pow-law with the dimensionless time t/（Oh·T）. In the tangential viscosity force dominant mode， maximal spreading factors are reached in the tangential direction.

Key words: droplet impact, rotating wall, viscosity, rotating speed, off-axis impact, spreading factor