Analysis of Dean vortices and sediment distribution in inlet passage of nearshore pump stations under solid-liquid two-phase conditions

Dean vortices are secondary flow vortices formed by the coupling effect of centrifugal and viscous forces when fluid flows through curved pipes. In nearshore pump station inlet flow passages, inhaled sediment interacts with Dean vortices, complicating flow patterns and intensifying passage abrasion. This study performs numerical simulations of the mixed-flow pump based on the Euler-Euler two-fluid model, with simulation results matching experimental data. Increasing pump flow rate enhances centrifugal force, driving Dean vortices and high-velocity flow toward the elbow outer wall and reducing their size, while promoting outward sediment accumulation and local concentration rise. Small-diameter particles exhibit intense interphase momentum exchange, inhibiting Dean vortex formation and creating low-velocity, low-concentration zones in the elbow. Large-diameter particles, with enhanced inertia and centrifugal force, strengthen vortex formation and sediment aggregation. Higher particle volume fraction increases the mixture’s density and viscosity; enhanced centrifugal force shifts Dean vortices and high-sediment zones outward, while increased secondary flow resistance suppresses vortices, reducing particle transport and forming a mid-section low-concentration zone. Elevated flow rate, particle size, and volume fraction boost centrifugal force and Dean number, with radial pressure difference peaks shifting synchronously. This study is significant for revealing sediment-laden flow laws and preventing passage abrasion.