A DNS Investigation of Aeroacoustic Noise Generation in Cold Spray Additive Manufacturing

Cold spray additive manufacturing (CSAM) technology is a solid-state deposition process applied to repair damaged components and fabricate individual components for aerospace, medical, and other important applications. CSAM uses a converging-diverging (CD) nozzle (exit diameter on the order of millimeters) to propel feedstock particles to a high velocity (higher than 300 m/s) and deposit the particles onto a substrate upon impact. In the CSAM process, the Mach number of the high-speed jet carrying powder feedstock can go beyond 2<!--[if gte msEquation 12]> style='mso-bidi-font-style:normal'>M=2, the Reynolds number (Re_D) beyond 5×10⁵, and the sound pressure level generated from the high-speed jet beyond 100 dB. In this study, we numerically investigate the aeroacoustic sound pressure level generated from the fully-developed circular turbulent supersonic jet. The flow dynamic variables of the jet are obtained by solving the compressible Navier-Stokes equations using direct numerical simulation (DNS). The simulation is performed in a CD nozzle with a nozzle pressure ratio of 1.1. The dominant frequency modes identified in the flow field can be diminished with a suitable sound mitigation strategy.