de Laval Nozzle with Thermo-Acoustic Regulation

Abstract

The invention relates to a portable cold spray system (10) for the deposition of metal powders in solid state at supersonic speeds and a hybrid de Laval nozzle (12) used in this system. In the invention, piezoelectric rings (16) mounted on the outer surface of the polymeric nozzle body (14) mechanically prevent ductile powders from adhering to the wall by generating high-frequency acoustic waves on the inner wall and accelerate the gas flow by disrupting the boundary layer. Simultaneously, the cryogenic nitrogen gas flow circulated from a cooling jacket (18) surrounding the nozzle body (14) keeps the inner wall temperature under control, preventing thermal adhesion and fouling. A powder injection port (20), located downstream of the nozzle bottleneck, passively delivers powder particles into the nozzle by the local vacuum effect created by supersonic expansion. The invention is used particularly in the field for dimensional restoration and corrosion repair of lightweight alloy and heat-sensitive aerospace components.