Cold Gas Dynamics Spraying Of Functional Coatings Flow Field Numerical Study

Cold gas-dynamic spraying technology is a new method for coating deposition that appeared in 1980's. Compared with those normal thermal spraying methods, the cold spraying technology has some distinguishing features that are of important advantages and has greater practical value and more application potential.In this paper, the jet flow in the cold spraying process is discussed. The aim is to acquire the distribution of those important variables through numerical simulation. And then, some evidence of how to optimize the parameters in the cold spraying technology experiments is offered. The CFD software PHOENICS is used in the flow simulation. The SIMPLEST algorithm which is a advanced edition of the SIMPLE algorithm is the numerical basics. The shock-capturing method is used to capture shocks. Through the numerical simulation, the distribution of those parameters such as speed, pressure of the free jet and impinging jet flow is obtained, also the position of shocks. The obtained numerical simulation results are compared with the jet dynamic theory, they are consistent. Some research is tried about the rectangular exit geometry nozzle in condition of only gas phase exists, aiming at analyzing its advantage to round nozzle in cold spraying technology.In the two-phase jet flow simulation, the two-fluid model is used to describe the dispersed particle phase. The IPSA algorithm, which is developed from the one phase SIMPLEST algorithm, is the mathematical basics. The simulation results show how the different diameter particle phase influences the flow field and how the gas phase influenced. Then, considering with the one-phase flow field together, some recommendations on particle diameter in cold spraying technology are given.