Influence of impeller-guide vane axial distance on the performance and flow characteristics of the gas-liquid-solid multiphase pump

[Objective] Multiphase rotodynamic pumps are widely used in multiphase mixed transport processes, including petrochemicals, agricultural irrigation, urban water supply, and drainage, attributed to their advantages of compact structure and good operation under high-speed and high-sand content conditions. The performance of these pumps is crucial for the transport capacity of the mixed transport system; thus, the improvement of their performance has always been a research interest. The impeller-guide vane axial distance of the gas-liquid-solid multiphase pump can seriously affect its transportation performance, but is rarely researched.[Methods] Herein, a multiphase rotodynamic pump with impeller-guide vane axial distances (d) of 8, 10, 12, 14, and 16 mm were modeled via UG-NX. The inlet and outlet pipelines, as well as impellers and guide vanes, were meshed via ICEM-CFD and TurboGrid, respectively. Based on the Euler multiphase flow model, computational fluid dynamics (CFD) numerical simulations were conducted to reveal the influence law of d on the comprehensive performance, including the head, efficiency, pressure, gas void fraction (GVF), solid void fraction (SVF), vorticity, and vortex structure for the gas-liquid-solid multiphase rotodynamic pumps.[Results] The adopted accuracy of the numerical methods was verified through experiments. The numerical results revealed that as d increased from 8 mm to 16 mm, the head and efficiency of the multiphase rotodynamic pump showed an overall decreasing trend; the head and efficiency of the pump declined by 0. 45 m and 1. 38%, respectively. As d increased from 8 mm to 10 mm, the head and efficiency of the multiphase rotodynamic pump declined by 0. 21 m and 0. 52%, respectively, which was recorded as performance plummet I; as d increased from 10 mm to 14 mm, the head and efficiency of the multiphase rotodynamic pump declined by 0. 09 m and 0. 12%, respectively—recorded as performance moderation; as d increased from 14 mm to 16 mm, the head and efficiency of the multiphase rotodynamic pump declined by 0. 15 m and 0. 74%, respectively—recorded as performance plummet T]. The change in d had a more significant influence on the flow state in the guide vane than that in the impeller. As d increased, the pressure difference decreased from the impeller inlet to the guide vane outlet, GVF at the trailing edge and SVF near the pressure surface at the leading edge of the guide vane blades gradually increased, the vorticity in the multiphase rotodynamic pump increased, and the vortex structure remained prominent, decreasing the overall pump performance.[Conclusions] The increase in d will reduce the head and efficiency of the multiphase pump and make the internal flow more turbulent. However, it will strengthen the rotor-stator interaction if d is exceedingly small. Therefore, the value of d should be selected from the performance moderation in the optimization design of such pumps. © 2024 Tsinghua University. All rights reserved.