Multiphase hydrodynamic flow characterization for surface finishing the laser powder bed fused AlSi10Mg conformal cooling channels

Abstract

Surface finishing additive manufactured internal passages using dynamic cavitation-assisted microparticle flow is becoming popular. The nucleation, growth, and collapse of the cavitation inside complex passages are crucial contributors for surface finishing and call for understanding for process improvement. In this work, we aimed to surface finish linear Direct Metal Laser Sintered (DMLS) AlSi10Mg conformal cooling channels (CCC). First, we surface finished the cooling channels with a square cross-section of width varying from 5 mm to 1 mm and length extending up to 50 mm using various multiphase finishing modes. Second, we characterized the multiphase flow with a high-speed camera and underwater hydrophone measurements, focusing on the cavitation effects, inside the cooling channels. Third, we performed numerical simulations and extracted cavitation and turbulent kinetic energy distributions inside the channels. The surface texture results were supported by cavitation frequency (nfo), root mean square pressure (Prms), and acoustic energy (EA) observations from the hydrophone. Finally, we explained the surface finishing trend by varying the channel size and length using numerical simulation results. The results suggest that the cavitation phase distribution decrease with a decrease in channel size and an increase in the channel length. The method proposed is useful in establishing appropriate process parameters to achieve a uniform surface finish along the entire channel length.