高速气流下金属线材熔融液滴形成及脱落过程模拟

Simulation of the Formation and Detachment of Droplets from the Molten Metal Wire in High-Speed Flow

摘要: 在等离子电弧喷涂(Plasma-arc wire spraying)工艺中，高速气流下金属线材的熔融与液滴的形成及脱离直接影响制备涂层的微观结构和质量。为了更好地理解熔滴形成及脱落的规律，本文建立了在高速气流驱动下金属线材熔融形成液滴及脱落过程的数学模型，对熔融金属的物理性质(表面张力、粘度、密度)以及入口流速对熔滴形成及脱落过程的影响分别进行了分析，结果表明表面张力与粘度越大，熔滴的脱落时间越长，主熔滴的脱落半径越大，其中表面张力占主导地位；密度与入口流速越大，熔滴的脱落时间越短，主熔滴的长度越长、脱落半径越大。

Abstract: The formation and detachment of droplets of the molten wire under conditions of plasma-arc wire spraying is a complex physical process, which is affected by various physical parameters. The melting of metal wires and the formation and detachment of droplets directly affect the micro-structure and quality of the coatings. In order to gain better understanding of the formation and detachment of droplets, a mathematical model of the processes of formation and detachment of droplets from the molten wire driven by high speed plasma gas is developed in this paper. The ef-fects of physical properties (surface tension, viscosity, density) and inlet velocity of molten metal materials on formation and detachment of droplets are analyzed. The results show that the larger the surface tension and viscosity, the longer the droplet shedding time and the larger shedding radius of the main droplet, in which the surface tension is dominant. The larger the density and inlet velocity, the shorter the droplet shedding time, the longer the length and the larger the shed-ding radius of the main droplet.