The development of multiphase pumps is restricted because of low efficiency and poor mixing transportation capacity. In this study, a two-step multi-objective optimization design system for a multiphase pump is constructed using a three-dimensional (3D) design theory and multi-objective optimization techniques. The transportability improvement for the pump impeller is achieved by implementing the optimization variables of its geometry and blade loading and the optimization objectives containing the pump efficiency and gas uniformity. The optimal results of impeller geometry show that the blade wrap angle and control parameters of the hub have remarkable effects on the pump efficiency and gas uniformity. The optimal results of impeller blade loading show that the pump efficiency is improved if the impeller with large loading at the leading edge, large slope at the middle part, and large negative high-pressure edge angle. The gas uniformity is improved if the hub loading at the middle and trailing parts is larger than the shroud loading. Compared to the original test impeller, the pump efficiency with the impeller T-Opt1 and the gas uniformity at the impeller outlet are improved by 10.81% and 6.91%, respectively. The maximum fluctuation amplitudes in T-Opt1 and its corresponding guide vane are reduced by 0.61% and 67.76%, respectively.

High-speed photography technology is adopted in this paper to systematically investigate the entire process of water jet breakup into droplets in the air after ejection from the water splitter tray of low-pressure rotary sprinklers under varying operating pressures and nozzle diameters. The experimental results revealed significant dependencies of jet breakup length, characteristic jet velocity, droplet characteristics, including their size and velocity, on the operating pressure and nozzle diameter. There are three types of spray water jet breakup, which are the split jet breakup, column jet breakup, and liquid-film jet breakup. A statistical linear regression model links the jet breakup length to the working pressure and nozzle diameter, and the breakup length of the water jet increases with decreasing working pressure or increasing nozzle diameter. Meanwhile, an increase in working pressure or nozzle diameter leads to a high flow rate, which in turn results in a power-law growth of the characteristic jet velocity. A quantitative nonlinear model of the breakup droplet velocity concerning its size and operating parameters is proposed through parametric analyses, and it is revealed that the breakup droplet velocity increases in a power-law manner with increasing pressure or nozzle diameter, and exhibits a logarithmic increase with increasing droplet size. This paper quantifies the relationships between jet breakup dynamics and operating parameters through experimental investigations and analytical modeling, which offers a valuable reference and experimental basis for performance-driven optimized design of industrial spray systems.

Pumping stations serve as critical hydraulic infrastructure for water conveyance and irrigation. Sediment deposition in forebays can deteriorate intake flow conditions, increase hydraulic losses, reduce pumping efficiency, and consequently impair the long-term operational performance of pumping systems. To accurately predict sediment deposition in complex three-dimensional flow fields, we developed a dynamics-driven boundary-responsive numerical model that integrates sediment particle dynamics with real-time bed evolution. This model adopts the near-bed vertical velocity of sediment particles as the deposition discrimination criterion and dynamically updates bed topography via a mass-conservation-based boundary response strategy. The proposed method was validated against open-channel experimental data. The simulated flow structures, deposition patterns, and temporal variations in deposition thickness agreed well with the measurements, with average deviations below 4%. Compared with conventional static-boundary numerical methods, the proposed model reproduces the coupled evolution of sediment transport, flow redistribution, and bed deformation with higher fidelity. The developed framework provides an effective numerical tool for sediment deposition prediction and offers practical support for hydraulic structure optimization, maintenance scheduling, and energy-efficient operation of pumping stations with sediment-laden flow.

αlVolume fraction of water phaseαgVolume fraction of gas phaseαpVolume fraction of particle phaseu,v,wVelocity vector (m/s)pPressure (Pa)∇Hamiltonian operatorρlDensities of water phase (kg/m3)ρgDen...