Particle velocimetry in cold spray and the pathway to a complete understanding of the data

Particle impact velocity and size are undoubtedly the most important control parameters in the cold spray (CS) process, and a few systems are now commercially available for in-flight particle velocity measurements. These velocity measurement techniques have a great potential to be used as a diagnostic tool. However, post processing the velocimetry data is required in many instances for achieving a complete understanding of the particle flow field. In this study, a pathway is presented for a comprehensive understanding of the entire particle flow field taking 6061 aluminum powder as an example case. In-flight particle flow conditions are measured using an Oseir HiWatch HR1 velocimeter in high Reynolds number helium and nitrogen jets generated by a VRC Gen III cold spray system. The powder particle size distribution (PSD) collected by the velocimeter is compared by measurements from a high-resolution optical microscope. The differences in the PSD data and the positional information are then statistically analyzed to capture a full picture of the particle flow field. 3D computational fluid dynamics simulations are then used to get a close approximation of the particle thermal and near impact conditions.