Effects of Secondary Air Flows on Thermal Characteristics and Particle Behavior in Flame Spray Process

초록

The present study investigates numerically the airflow and thermal characteristics as well as the transient behavior of different particles such as nickel, copper, titanium, and tungsten during the flame spray process by using the computational fluid dynamics (CFD) code (Fluent Ver. 13.0). The combustion model was used in conjunction with the Arrhenius model to describe multi-component turbulent flows occurring during a chemical reaction. It was found that secondary air increased flame temperature and changed the flow direction which can affect the particle behavior. Further, the particle velocity and temperature rapidly changed with the decrease in particle size, causing faster absorption of thermal energy from the hot gas. Moreover, the particle experiences the phase change depending on the temperature and its phase significantly depends on the variation of heat capacity of selected particle. Because the particle phase prior to impact on the sample surface determines the quality of the coating layer, the secondary air pressure should be controlled carefully together with considering the particle type.

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