Traditional vortex shaft spillways are prone to cavitation and structural degradation under high-head, high-velocity flow conditions. To address these challenges, this study proposes a tapered vortex shaft configuration. Numerical simulations using the Volume of Fluid (VOF) method and the RNG k–ε turbulence model were conducted to compare the tapered and conventional designs in terms of flow behavior, velocity and pressure distributions, and cavitation resistance. Results show that the tapered geometry facilitates smoother velocity and pressure transitions, promotes the formation of a stable vortex core, and extends the effective flow path. These features enhance energy dissipation and significantly reduce low-pressure zones, thereby improving cavitation resistance. The findings provide a basis for optimized vortex shaft designs in high-head hydraulic systems.

tapered vortex shaft, cavitation erosion, cavitation resistance, numerical simulation