Analysis of the impact velocity of powder particles in the cold-gas dynamic-spray process

While built on a sound physical foundation, isentropic, one-dimensional models generally used to analyze the dynamics of dilute two-phase (feed-powder particles suspended in a carrier gas) flow during the cold-gas dynamic-spray process, require the use of numerical procedures to obtain solutions for the governing equations. Numerical solutions, unfortunately, do not enable an easy establishment of the relationships between the gas, process and feed-powder parameters on one side and the gas and the particle velocities at the nozzle exit and the particle impact velocity, on the other. Analytical solutions for the governing equations in the limits of small and large relative particle/gas velocities and a multiple non-linear regression analysis are used, in the present work, to develop analytical functions which can be used to compute the gas and the particle exit velocities and the particle impact velocity for a given set of the gas, process, and feed-powder parameters. The results obtained using the analytical functions are found to be in a very good agreement with their numerical and experimental counterparts. (C) 2003 Elsevier B.V. All rights reserved.