Study of spreading, vibration, and fracture behavior of double droplets after positive collision

Abstract

The droplet collision phenomenon is a more complex heat and mass transfer phase transition phenomenon, which is subject to the joint action of kinetics and thermodynamics. During the collision process, the mutual fusion interference of double droplets makes the kinetic mechanism after droplet collision more complicated, and its in-depth study can provide important theoretical support for the fields of engineering applications, industrial production and wetted wall design. In order to investigate the kinetic behavior of double droplets positive collision, this paper mainly combines experimental and numerical simulation methods to investigate the spreading, vibration and fracture characteristics of double droplets of the same volume after collision. Firstly, the rebound vibration of the fused droplet and single droplet is equivalent to a single-degree-of-freedom damped vibration system, and the spreading and vibration characteristics of the single droplet and the double droplets after collision under the same collision velocity are analyzed comparatively by experimental methods. The results show that when the droplet does not fracture, the spreading factor and damping coefficient of single droplet and double droplets gradually increase with the increase of collision velocity, and the vibration time gradually decreases. The damping coefficient and vibration time of the double droplets are higher than that of the single droplet, while the spreading factor is lower than that of the single droplet. Then, the double droplets positive collision phenomenon is studied in depth, and it is found that the spreading factor of the fused droplet increases with the increase of the droplet diameter, the collision velocity, and the wall contact angle. Affected by the low wall temperature, the fused droplet undergoes a phase transition, which affects the bottom flow of the droplet, leading to an increase in the damping coefficient and a decrease in the vibration time. With the decrease of the collision velocity and wall contact angle, the damping coefficient gradually increases and the vibration time decreases. Finally, the numerical simulation method reveals that rebound fracture and spreading fracture phenomena occur after double droplets positive collision, and the critical values of the collision velocity required for the occurrence of rebound fracture and spreading fracture are found. This provides a reliable theoretical basis for the study of the heat and mass transfer process after the collision of multiple droplets on the wall.