Cold gas dynamic spray process: CFD modeling and simulation of high-speed(supersonic) two-phase (gas-particle) aerodynamic flow behavior
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Date
2020
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University of New Brunswick
Abstract
Cold gas dynamic spray (CGDS) is a solid-state material additive manufacturing method whereby feedstock particle is accelerated in a high-pressure, but low-temperature, environment to create a supersonic aerodynamic condition. The outcome is a thin deposit or a 3D freeform object with significantly low residual stress in the underlying material microstructure, hence superior mechanical strength. In this research, a systematic literature review of the CGDS state-of-the-art, an explanation of the fundamentals of gas dynamic principles, and a derivation of a two-phase (gas-solid) material transport model based on computational fluid dynamics (CFD) and Lagrangian particle tracking theories are carried out. The mathematical methods implemented to model the two-phase system are based on 1) the approach to characterize supersonic flow inside the DeLaval nozzle and its surrounding; and 2) the integration of an existing drag coefficient model with the Lagrangian particle tracking in ANSYS CFX code, with an ultimate goal to simulate the particle kinetic velocity in a supersonic environment. A comparison is made between the numerical particle velocities and the experimental particle velocities based on the parametric study of the drag coefficient model mentioned above. Last but not least, a discussion concerning the effectiveness of the available drag coefficient models and their best practices to characterize particle velocities is conducted, which has highlighted the need for a future study on a comprehensive drag coefficient model development.
Keywords: Cold gas dynamic spray; Supersonic De-Laval nozzle; Computational fluid dynamics; Lagrangian particle tracking; Drag coefficient model