Effects of Curvature on the Flow Characteristics and Particle Behavior in the Flame Spray Process

Abstract

The present study investigates numerically the thermal and flow characteristics and transient particle behavior in the conventional flame spray process by using the computational fluid dynamics (CFD) code (ANSYS Fluent V. 16.1). From geometrical consideration, it is noted that the deposition angle of a particle decreases drastically on a curved surface because of the curvature effect, and significantly affects the normal impact velocity of the particle. Numerical results indicated that the normal component of the particle impact velocity on the curved surface was lower than that on a flat surface by up to 5.7%. This result is significant with regard to the adhesive characteristics, as binding energy with the substrate is proportional to the square of the particle's normal impact velocity. The influence of spray distances and radius of the curved substrate were examined and the corresponding results would be useful in finding optimal operating conditions for the curved substrate. It was observed in this study that the spray distance exhibited a more dominant effect on the particle impact velocity, substantially associated with the coating quality of the deposited layer.