关键词: 液滴撞击, 凸表面, 凹表面, 液滴动力学, 传热

Abstract: In the majority of prior research, the phenomenon of droplet impact on solid surfaces has predominantly been examined under conditions involving flat substrates, with pure water serving as the most frequently utilized working fluid. While such studies have provided foundational insights into droplet dynamics, their applicability remains limited, as they fail to address the complexities encountered in many industrial and engineering scenarios. By contrast, investigating the impact behavior of ethanol droplets on cylindrical curved surfaces offers substantial practical value, particularly in optimizing critical industrial processes such as spray cooling and surface coating. Beyond industrial applications, this research also contributes to advancing fundamental knowledge in multiphase flow systems, particularly in understanding how interfacial interactions between liquids and curved substrates influence spreading, rebound, and heat transfer mechanisms. This study employs experimental methods to investigate the dynamics and heat transfer mechanisms of pure ethanol droplets and ethanol-glycerol mixture droplets (with a certain amount of glycerol added) impacting overheated curved surfaces. The dynamic analysis reveals that for pure ethanol droplets, the behavioral differences caused by surface curvature primarily occur in the high Weber number (We) regime. After adding glycerol, the maximum spreading factor on concave surfaces increases with higher glycerol concentration in the droplet, whereas on convex surfaces, this relationship no longer follows a linear trend. In terms of heat transfer, the study demonstrates that the heat transfer mechanisms differ between low and high wall temperature conditions during continuous ethanol droplet impact on overheated surfaces. Moreover, there is a coupling effect between glycerol concentration and surface curvature on heat transfer characteristics. For the impact of droplets on concave surfaces, the addition of glycerol enhances heat transfer performance at low wall temperatures; whereas at high wall temperatures, when the temperature increases to a certain extent, the addition of glycerol has no significant effect. In contrast, for droplet impact on convex surfaces, glycerol addition enhances heat transfer performance only under high wall temperature conditions.

Key words: droplet impact, convex surface, concave surface, droplets dynamics, heat transfer