Numerical Simulation Of Gas-Particle Two Phase Flow In Cold Spraying Process

The gas axis velocity and particle velocity in and out of the nozzle have great influence on the coating effect in the process of cold spray, It is very important to study the effect of different spray Parameters on gas axial velocity and particle velocity. Although many scholars research gas-particle two phase by numerical simulation,but mostly without considering the influence of the substrate, research of parameter optimization for cold spraying is also less.We obtained the influence of different spray parameters on gas and particle velocity by studied the gas-solid two phase flow in cold spray using numerical simulation. First establish physical model of jet region and dividing the grid and define boundary conditions,Then a two-dimensional mathematical model is presentedand used to study the flow. Research the effect of different carrier gas ,pressure, temperature and spraying distance on gas velocity .Finally discrete phase model is establish to numerical simulation the two phase flow, seperately accelerate Ti, Cu and Au power,Every material select different diameters,get the accelerate characteristics of different materials and the same material with different particle diameter.Simulation results show that the acceleration of helium is better than nitrogen and air.With the spray temperature and pressure increased, the gas axial velocity and particle velocity also increase.Differernt spray distance have no effect on the flow in the nozzle. Improve spraying temperature can significantly improve spraying effect.Smaller particles with low density can not obtain a high-speed because their inertia are small, so the particle speed and direction easily changed with the vortex flow before the substrate. larger particles with high density also not easy to be accelerated to a higher speed, because their inertia too big, these are bad for spraying. material particles should be in an appropriate range,and we should select appropriate coating parameters according to material density and particle diameter. It will offers reference for cold spray experiment and optimize the spray parameters.