Wake topology and vortex structure evolution of a marine propeller with a fractured blade

This study investigates the wake evolution and vortex instability mechanisms of a marine propeller under blade fracture conditions, with the objective of understanding how severe structural damage alters propulsive flow dynamics. High-fidelity simulations were conducted using the improved delayed detached-eddy simulation approach on a grid of 66.9 × 106 cells. A comparative analysis with an intact propeller was performed to evaluate the impact of fracture on wake topology and flow behavior. The results reveal that blade fracture significantly modifies the tip vortex system, leading to two distinct and successive vortex merging events at different downstream and radial locations. These merging processes are driven by mutual inductance and exhibit a leap-frogging mechanism, in which smaller vortices overtake and merge with larger ones. This sequence substantially enhances turbulence intensity and alters energy transfer within the wake. The instability of the tip vortex system was also found to directly influence the development of hub vortex instability, which was suppressed following the completion of tip vortex merging. These findings provide theoretical insights into the fluid dynamics of damaged marine propulsors and offer a physical reference for developing predictive tools and safety assessment strategies under extreme operating conditions.