Effects of Surface Tension on Drop Impact on a Horizontal Rotating Disk

The impact processes of water and ethanol drops on a rotating horizontal aluminum disk were recorded and analyzed using a high-speed digital camera together with an image analysis program. The angular velocities of the disk were altered to study the effect of surface tension of drops on drop impact processes. The experimental results show that a lower surface tension will result in a higher tangential spread factor and a lower receding rate during the receding stage, for the drop impinging and depositing on a rotating disk. In addition, a lower surface tension of the drop tends to promote the occurrence of splash. The experimental results further verify a proposed correlation of splash-deposition boundary for drops impinging on a rotating disk. Both drops, though they have a quite different surface tension, experience four stages, with two new stages different from those of drops impinging on stationary surfaces. Their tangential spreading factors both increase obviously with the tangential velocity at the impact point, while their radial spreading factors vary a little.