Multiphase coupled numerical simulation of HVOF thermal spraying: Flight behavior and turbulent dispersion of CoCrFeNiMo0.2 high-entropy alloy particles

High-velocity oxygen fuel (HVOF) spraying is an advanced surface modification technique for depositing high-performance high-entropy alloy (HEA) coatings on engineering components, and the coating quality is strongly influenced by the in-flight behavior of HEA particles within the flame jet. In this study, a numerical model of the HVOF flame jet was first established to investigate the effects of kerosene-oxygen combustion on the pressure, temperature, and velocity characteristics of the jet. On this basis, a multiphase coupled model describing the interaction between CoCrFeNiMo 0.2 HEA particles and the flame jet was further developed to analyze particle heat and momentum transfer as well as turbulent dispersion behavior. The effects of kerosene and oxygen flow rates and their ratio, initial particle parameters (particle size, sphericity, injection velocity, and flow rate), and spraying distance on particle temperature evolution, acceleration behavior, and spatial distribution were systematically investigated. The numerical results showed good agreement with the stagnation-point spraying experiments. The results demonstrate that appropriate regulation of the fuel-oxygen conditions and particle injection parameters can promote sufficient particle heating and effective acceleration, reduce the probability of particle collisions with the inner nozzle wall, and establish a stable and controllable spraying process window. These findings provide a theoretical basis and engineering guidance for process optimization and the controlled fabrication of high-quality HEA coatings.