Experimental study on the secondary droplet formation mechanism when droplet impacting on superheated surface. (April 2022)

• Record Type: Journal Article
• Authors: Chen, Mingjing; Chen, Deqi; Liu, Yu; Liu, Haidong; Liu, Hanzhou
• Is Part Of: International journal of heat and mass transfer. Volume 185(2022)
• Publication Date: 2022-04
• Subjects: Secondary droplet -- Visual experiment -- Mechanism -- Superheated surface; Heat -- Transmission -- Periodicals; Mass transfer -- Periodicals; Chaleur -- Transmission -- Périodiques; Transfert de masse -- Périodiques; Electronic journals; 621.4022
• DOI: 10.1016/j.ijheatmasstransfer.2021.122412
• Languages: English
• ISSNs: 0017-9310

Abstract

Highlights: Secondary droplet formation mechanism after droplet impact on hot wall is discussed. Quantitative analysis of size and velocity distribution of secondary droplets is presented. Breaking model of droplet on hot wall is proposed with good prediction. Abstract: When a droplet impacts a superheated surface, due to the different effects between wall superheat and the initial Weber number of the droplet, secondary droplets will be generated by different mechanisms due to the coupling effect of kinetics and temperatures, such as fracture, spray, atomization, and breakup. In this paper, a visual experimental study is conducted based on the effects when droplets impacting on the superheated wall. The wall temperature ranges from room temperature to 650 °C, and the droplet Weber number ranges from about 10 to 500. Based on the sequence images of droplets taken by a high-speed camera, three of four secondary droplet mechanisms (excluding fracture droplets) are presented and discussed in detail. Furthermore, the size and velocity distribution of the secondary droplets under different mechanisms are quantitatively analyzed through image processing. Finally, an edge-breaking model of the droplet with a high-temperature wall is proposed considering the evaporative momentum force near the triple-phase contact line, and it is in good agreement with the experimental results.