An Analysis of Radial Cold Spray Nozzles



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Cold spraying, also known as gas dynamic cold spraying or supersonic particle deposition, is an additive manufacturing technique wherein powder particles are accelerated by a carrier or driving gas passing through a supersonic nozzle and impinged on a substrate. Powders used in cold spray range from a metal, alloy, polymer, or composite powder material. In the past this technique has primarily been used to form protective coatings for surfaces, but the process is also used for the repair and restoration of damaged or worn parts, or to machine a part that would be difficult or impossible to otherwise create. Although cold spray has many benefits over similar fabrication and restorative processes due to less heat stress on the substrate, a key concern arises when considering small, internal surfaces. Cold spray relies on the high velocity of the particles—rather than on their temperature—to bond with the substrate. When repairing an internal surface that is too narrow for the full nozzle to fit into, it must be bent to accommodate the smaller diameter. This bend of the nozzle provides an additional surface for the particles to hit, causing either clogging or erosion of the nozzle interior, depending on the impacting particle’s velocity. In this project, previous radial cold spray nozzle designs were assessed and compared with revised versions to determine a more optimal design for a radial cold spray nozzle.



cold spray, additive manufacturing, nozzles, CFD, computational fluid dynamics, compressible flow, supersonic flow