The demand for a centrifugal pump with open impellers for conveying dense fine particles in solid-liquid two-phase flow has increased significantly in actual engineering. The wear of dense fine particles on the centrifugal pump is also exceedingly prominent, which affects the engineering efficiency and economic benefits. The two-phase flow in the open centrifugal pump is three-dimensional and unsteady; the movement of high-volume concentration particles in the centrifugal pump and its mutual influence on the two-phase flow, which results in the calculation of wear, are very intricate. To study the wear characteristics of the centrifugal pump with open impeller with high-volume concentration particles more accurately, numerical simulation and experimental comparison are carried out for the impeller wear of dense fine particles transported by the centrifugal pump with open impellers. Considering the relationship between particles and walls, we used the Fluent 18.0 built-in rebound function and wear model. The RNG k-ε model and the DDPM model were adopted in the numerical simulation, and the numerical solution for centrifugal pump wear was performed under flow rate (9.6 m3·h−1, 12.8 m3·h−1, 16 m3·h−1, and 19.2 m3·h−1), different particle sizes (0.048 mm, 0.106 mm, 0.15 mm, 0.27 mm, and 0.425 mm), and different particle volume concentrations (10%, 15%, 20%, 25%, and 30%), respectively. By comparing the serious wear positions of the impeller, the experimental results correspond well with the numerical simulation, which can be used to predict and study the wear characteristics of the impeller. The results show that the most serious area of blade wear is the middle part of the pressure surface, followed by the middle part of the upper part of the blade. The wear of the impeller is greatly affected by relevant parameters, such as pump flow rate, particle diameter, and particle volume concentration. These results can provide some basis for the wear-resistant design of dense fine particle impeller.
In the energy conversion device and fluid transport equipment, the solid–liquid two-phase centrifugal pump occupies a large proportion, but the transport mechanism of dense fine particles has not been studied in detail. In this work, the solid–liquid two-phase flow in a centrifugal pump was numerically simulated by the mixture model. Two-phase performance tests with different particle concentrations and particle sizes at a low flow rate (0.6Qd) were conducted, and dimensionless analysis on the effect of particle concentrations and particle sizes on head and efficiency was conducted. The results show that the increase in particle size and particle concentration can increase the influence coefficient of head and efficiency and the influence of the two parameters on efficiency is greater than that on the head on the whole. The increase in particle size and concentration will lead to more uneven distribution of the solid volume fraction in the pump. The transport of dense fine particles absorbs a large amount of energy, which leads to the relative decrease in the kinetic energy of the liquid phase and inhibits the generation of the vortex in the impeller passage.
A centrifugal pump is an important solid–liquid mixture conveying machinery, which is widely used in mineral mining, water conservancy engineering, and other fields. Solid particles will wear the impeller of the centrifugal pump in the process of transportation, resulting in lower service life of the impeller, especially in the transportation of a high concentration of solid particles. Many scholars use numerical simulation to study the wear of centrifugal pumps, but few efforts have been made in the wear experiment. In this study, the effect of three factors, namely, diameter of solid particles, mass concentration of particles, and material of impellers on the wear of a solid–liquid two-phase centrifugal pump was studied by the wear experiment. The solid particles are SiO2 with irregular shapes, and the diameter ranges are 0.125–0.212 mm, 0.212–0.425 mm, and 0.425–0.710 mm. The mass concentration of solid particles is 15%, 20%, and 30%. The material of impellers is carbon structural steel (Q235), gray cast iron (HT200), and low-alloy high-strength steel (16 Mn). The amount of wear is determined by measuring the thickness of the impeller material before and after wear experiments. The wear morphology of the impeller was observed by using a digital microscope. The results showed that the wear mainly concentrated on the middle and trailing edges of the blade. Impellers of different materials suffer different wear forms, among which the impeller made of HT200 has the best erosion resistance. The increase of solid mass concentration will aggravate the wear of the impeller. The change of particle diameters also has a great influence on impeller wear.
The solid–liquid two-phase centrifugal pump is one of the core power equipment of solid phase material hydraulic transportation, widely used in hydraulic engineering, petrochemical industry, marine metal mineral exploitation, urban sewage treatment, and other sectors of the national economy. There is a significant increase in the need to transport dense fine particle slurry in industrial production. Under this condition, the influence of particle parameters on the performance of the centrifugal pump is still not clear. In order to study the flow and wear characteristics of dense fine particle solid–liquid two-phase transported by an open impeller centrifugal pump, the Re-Normalization Group k − ε and dense discrete phase models in Fluent were used to describe the characteristics of the solid–liquid two-phase flow. The numerical model is validated with the experimental data of the pump’s performance. The study indicates that the particle size and concentration have great influence on the wear of the impeller. The wear of the blade pressure surface is the most serious. With the increase of particle concentration and size, the wear area expands to the leading edge and the upper surface of the blade. These results can provide supporting theories for the design of a dense fine particle solid–liquid two-phase medium conveying pump.
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