This paper investigated the role of particle injection on inflight particle behavior and its coupling effect on plasma plume in an external orthogonally injected air plasma spray system as well as effects of primary, secondary and carrier gases on in-flight particle status through both experiments and simulations. Diagnostic sensors such as In-flight Particle Pyrometer (IPP) and Spray Position Trajectory (SPT) have been used to obtain the plume characteristics and ensemble temperature, while DPV-2000 was used to measure the distributions of individual particle status such as temperature, velocity and size at the maximum particle flux point. Three-dimensional simulations have been carried out for the corresponding experimental conditions to examine the effects of in-flight particle heating on the plasma plume and in-flight characteristics at different spray distances. Both experiment and simulation results show that particle temperature and velocity will initially increase with plume angle and then decrease after reaching a maximum value for different combination of process parameters at the same plume angle. Theoretical analysis shows strong dependence of the plume angle on the velocity ratio of vertical component from the carrier gas to the horizontal one from primary and secondary gas at their respective nozzle exits. This study enables a better understanding of influence of plasma forming and stabilizing parameters on the particle in-flight characteristics.

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