Sediment Wear Characteristics of a Bulb-Type Tubular Turbine under Varying Sediment Concentrations and Cavitation Conditions

To investigate the wear characteristics of bulb‑type tubular turbine under sediment-laden cavitation conditions, this study examines the wear mechanisms of this turbine under the combined effect of particles and cavitation. Numerical simulations of sediment erosion were conducted for the turbine under different particle concentrations, based on the Euler–Lagrange approach and the Tabakoff wear model, considering both solid–liquid two-phase flows and solid–liquid–vapor three-phase flows. Comparison of sediment erosion under cavitating and non‑cavitating conditions reveals that, under sediment-laden solid–liquid two-phase flow conditions, an increase in particle concentration increases wear. The wear rates of the draft tube, runner chamber, guide vanes, and runner increase with particle concentration. In contrast, the wear in Region 1 on the strut initially decreases and then increases as particle concentration increases. Additionally, the pressure on the bulb and guide vanes, as well as the turbulent kinetic energy in the draft tube, increase with particle concentration. Under sediment-laden solid–liquid–vapor three-phase flow conditions, wear varies considerably among turbine components. Particle concentration shows a positive correlation with the wear of the draft tube, runner chamber, and guide vanes. Notably, within the runner chamber, the runner experiences the most severe wear at a particle concentration of 4.5 %. Cavitation increases the pressure on the guide vanes and bulb wall surfaces, while it suppresses the turbulent kinetic energy in the draft tube and mitigates wall erosion.