Pumps are one of the most important equipment in deep-sea mining system, which transport particles continuously from the seafloor. In this paper, the computational fluid dynamics−discrete element method (CFD−DEM) numerical simulation was used to analyze the effect of particle volume fraction (PVF) on the particle transport mechanism in the pump. The reliability of the CFD−DEM numerical simulation was verified by high-speed photography experiments. The results show that the particles mainly move along the blade pressure surface (BPS) in the impeller, and the particles can suppress the formation of low-velocity vortices on the BPS. The translational velocity of the particles is less affected by the PVF, but has a significant effect on the rotational velocity. The flow pattern of particles inside the volute is categorized into wake flow, cutting flow, and near wall flow. With the increase in PVF, the particles are subjected to pressure gradient force, drag force, and virtual mass force in the pump gradually increase, but the lift force on the particles gradually decreases. The tangential force and normal force between particles increased with increasing PVF, and the increase in PVF from 2% to 10% was 462.55% and 148.17%, respectively. The collision frequency per unit time of particles with volute is the largest, but the collision frequency per unit time and per unit area is the largest for impeller. The most significant impact work of particles with volute and particles with blades is 371.08% and 505.66% when PVF increases from 2% to 10%. This study can provide theoretical guidance for the optimal design of solid−liquid two-phase pumps.
Abstract Inducer has many design parameters and is an important hydraulic component to improve cavitation performance of pump, yet there are no mature methodologies completely determine the geometrical parameters for inducer. The design parameters of general industrial inducers are divided into performance ones and geometric ones, the latter are further subdivided into four kinds, matching ones, blade angle ones, cascade ones, and et al. There is a relation between cascade solidity and tip length-diameter ratio, but the two are currently only selected based on experience. It is not clear to determine the optimal values of them in current inducer design. In this paper, the relationship between the parameters and inducer performance is analyzed, and the origin of how and why to determine the value of the parameters is investigated. Three principles by which reasonable inducer can be designed is summarized. The relationship between cascade solidity, length-diameter ratio and blade number and some problems related are analyzed. Finally, the pump of cavitation speed is 870 is selected as an example to design the inducer, subsequently the original vibration is effectively eliminated by installation of the inducer.
Turbulence modeling plays an important role in the accurate prediction of turbulent fluid motion in computational fluid dynamics simulations using the Reynolds-averaged Navier–Stokes equations. A new one-equation Wray–Agarwal (WA) turbulence model has recently been developed by the present authors to improve the prediction of nonequilibrium turbulent flows with large separation and curvature. In this paper, the WA turbulence model is employed to simulate the internal turbulent flow characteristics in a U-bend, and the computed results are compared with experimental data. The results obtained from four other commonly used turbulence models, viz., the one-equation Spalart–Allmaras, two-equation standard k-ε, renormalization group k-ε, and shear stress transport k-ω models, are also compared. Detailed experimental data are obtained using magnetic resonance velocimetry. The results computed with the five different turbulence models show that the WA turbulence model gives the highest accuracy in predicting the complex three-dimensional turbulent characteristics of flow with large curvature in a U-bend.
This chapter describes a typical experimental apparatus including the equipment and measuring instruments, mixed-flow pump test model and testing methods, calibration, data collection, and analysis. In particular, the energy performance test, pressure pulsation monitoring, particle image velocimetry (PIV) measurements, and axis orbit signal of a mixed-flow pump are described and analyzed. The experimental details provided here can help an investigator in planning the experiment and obtaining useful data for evaluating the performance of a pump.
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