A concept of Aerospike Nozzle for Cold Spray Additive Manufacturing: towards a potential solution for preventing the issue of clogging. / Investigation of a Modified Circular Nozzle for Cold Spray Applications
The aim of this study is to improve the nozzle for cold spraying to get a high efficiency and to prevent the clogging phenomenon. Different types of nozzles are investigated by using a CFD analysis to compute the Mach number, the velocity, and the temperature of the supersonic gas for a high and a low-pressure inlet. To avoid the issue of easy clogging that occurs on the inner wall of the conical nozzles or the bell nozzles, due to a high thermal exposure, a concept of separate channel that feed the powders within the supersonic core outside the nozzle is investigated. A secondary cold gas flow drives the powders for that purpose but the mixture of this gas with the supersonic gas can create a turbulent flow. Then, the powders flow can be disturbed by the turbulence so that their trajectory becomes difficult to control. A solution for the recirculating of the turbulence will help to control the powder flow in a uniform way.
Investigation of a Modified Circular Nozzle for Cold Spray Applications
Despite the fact that the supersonic nozzle is critically important to the cold spray process, limited studies have been conducted on nozzle designs that enhance deposition efficiency & build quality [1] while at the same time reducing the bottlenecks in continuous operation i.e. higher consumption of the carrier gases and clogging phenomenon. The existing conventional nozzle design, which includes the powder feeder tube and both the convergent and divergent sections, is the subject of this study's attempt to improve it. The aim is to achieve a superior bonding of powder with the substrate and reduce the clogging issue. Different internal nozzle geometry changes were adapted to direct the particles away from the diverging wall as a means of preventing collisions where clogging typically occurs. Following the numerical simulation investigation the most promising designs will be experimentally tested to analyse their performance. Additionally, the study will also investigate different nozzle materials and the effect of a reduction of the divergent length. The longer divergence length leads to a reduction in gas centreline velocity compared to the designed value due to frictional losses and boundary layer effects which reduces the effective transfer of momentum to the particles.