Numerical simulations of pump/intake interactions under non-uniform incoming streamtubes for Outboard Dynamic-inlet Waterjets

This study presents a numerical investigation of off-design performance in an Outboard Dynamic-Inlet Waterjet (ODW) operating under distorted inflow conditions. Leveraging recent advances in marine propulsion, the ODW is modeled independently from the ship as an axisymmetric nacelle housing a propulsive pump. Expanding on existing research focused on nominal ODW conditions, this paper explores a free-stream incidence angle of 16◦ using a full annular model. The model couples an axisymmetric inlet with an axial-flow pump rotating counterclockwise at 1400 rpm. Unsteady Reynolds-Averaged Navier-Stokes (URANS) simulations, conducted over five impeller cycles, account for turbulence and cavitation using the k-ω SST and Zwart models, respectively. The results reveal the development of a vortex in the lower-right quadrant of the intake, reducing pressure on that side and promoting cavitation on the blades advancing through the right. Additionally, flow separation on the nacelle's outer walls near the stagnation point leads to a cavitation cloud symmetrically covering a 114◦ sector around the propulsor mid-plane.