Parametric Redesign of a Convergent-Divergent Cold Spray Nozzle

The current study investigates titanium cold spraying. The redesign of a cold spray convergent-divergent nozzle is achieved by application of two aerospace design codes based on the Method Of Characteristics (MOC). By Computational Fluid Dynamics (CFD), the performance of a current commercial cold spray nozzle is compared with a new nozzle profile designed with a smooth throat and for a parallel (axial) outflow. The CFD model uses a coupled Eulerian-Lagrangian formulation where steady axisymmetric Reynolds-Averaged Navier–Stokes (RANS) SST k-ω model is used to resolve the dynamics of the continuous phase and the Discrete Phase Model (DPM) is used to compute the motion of the particles. The particle acceleration process is also investigated by determining the optimal gas condition which is obtained by differentiating the drag force with respect to the Mach number.

The CFD results for the jet spreading rate, the velocity centerline distribution, and the particle velocity show the tangible benefit redesigning the cold spray nozzle by application of classical gas dynamics. The outcome is a new nozzle design with higher particle velocity obtained at the same operating conditions/costs used by the industry standard nozzle.