Experimental study on spreading and breaking mechanism of droplet impinging on low temperature wall at high speed

In order to study the dynamic behavior of a droplet impinging on a low-temperature wall, a visualization test was carried out on a single droplet impinging on the normal temperature （22 ℃） and low temperature wall （−30 – −10 ℃） with the Weber number between 533 and 1630 by the high speed shadowing method. The experimental results show that prompt splash and corona splash occurs when the droplet impinges on the low temperature wall at the certain speed, and the splashing of secondary droplet is obvious. However, when the droplet impinges on the normal temperature wall at the same speed, there is no droplet breakage phenomenon. With the decrease of the wall temperature, the Weber number required for the droplets to smash into the wall decreases. When the wall temperature is −30 ℃, the critical Weber number of the droplet crashing into the aluminum plate decreases to about 480. When We < 480, even if the wall temperature is lower than −30 ℃, the droplets would not smash into the wall. When the droplet hits the normal temperature wall, the droplet spreads out rapidly, and the larger the Weber number is, the greater the spread and retraction speed of the droplet is, and the larger the spreading factor of the droplet is. This study provides a reference for the establishment of the impingement model of the droplet impinging on the low temperature wall surface.