Some Observations on Particle Size and Velocity Measurements using Phase Doppler Anemometry in Plasma Spray

摘要

Applications of Phase-Doppler anemometry to the measurements of metal (nickel) particle size and velocity in the plasma spray process have been studied and analyzed with the aid of Mie scattering theory. The optimum optical settings used in two PDA systems were determined and tested experimentally. Measurements at cross-sectional planes 5 and 10 cm below the SG-100 (Miller) plasma gun were obtained and discussed. In this study, only one particle injection port was used. It is noticed that the variation of the percentage of the diameter validation rate would affect the volume flux results considerably. If the diameter validation rate can be maintained above 65%, the integrated volume flux would be close to the results obtained from the total volume deposited on a substrate or from the estimation based on the mass balance in the powder feeder (measured before and after spraying). The PDA measurement may also provide some predictions on the deposition area and the corresponding maximum height of the coating at a specific stand-off distance from the nozzle.