Numerical simulation and mechanism analysis of hydrogen fuel HVOF spraying process based on EDC and EDM combustion models

High-Velocity Oxygen-Fuel (HVOF) spraying is an advanced surface treatment technique. Combustion reactions directly govern the in-flight behavior of spraying jets and particles. Quantitatively analyzing these mechanisms is therefore essential for high-quality coating fabrication. This paper conducts a numerical simulation study on the HVOF thermal spraying process using hydrogen as the fuel by establishing a 2D axisymmetric computational fluid dynamics (CFD) model for the JP5000 spray gun. The model included combustion process, spraying flame flow injection process and the flight characteristics of the particles. Using hydrogen as fuel, the process of spraying magnesium alloy substrate was solved by numerical calculation. Flame dynamics and dispersed particle phases were simulated under contrasting combustion models: Eddy Dissipation (EDM) and Eddy Dissipation Concept (EDC). Computational results demonstrate that under the EDC model can be used to quantify the effects of multi-step chemical reaction and small-scale turbulence on the combustion reaction rate, and the calculation results of the EDC model are smoother and more stable. The results demonstrate that the EDC model, with its detailed chemical mechanism, provides fundamentally different and more physically plausible predictions of the flame and particle conditions, underscoring its necessity for high-fidelity modeling of advanced thermal spraying processes.