| The HVOF process is used for coating protective layers on surfaces exposed to corrosion and wear. This process involves a supersonic two-phase flow of gas-solid particles. The main objective of this thesis is to explore certain key factors that influence the process efficiency such as gas-particle interactions, particle in-flight conditions, and particle loading.;To find the effect of particle loading on the gas phase, a dense particulate phase scenario is assumed. A fully Eulerian approach, which treats the particles as a fluid, is used to simulate the HVOF process and the two-phase flow characteristics were investigated for various particle loadings. The particulate phase was found to be dense near the nozzle centerline and dilute near the wall. In the particle-dense region, the gas phase characteristics were found to be severely affected, which significantly affects the particle velocity.;To study the effect of gas-particles interactions, a Lagrangian approach which tracks individual particles in the continuous gas, is used. The supersonic gas flow leaving an HVOF nozzle is over-expanded and its adjustment to the atmospheric pressure results in shock diamonds formation, while flow impingement on a substrate results in bow-shock development. Both the shocks are responsible for affecting the particle conditions. The strength and location of bow shock vary for different substrate geometries and stand-off distances. In this work, various particle sizes impinging on different substrate configurations are simulated and the particle interactions with both the shocks are presented in detail. |
