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<p>This study investigates the fluid dynamics of cavitation vortices in centrifugal pumps, with a specific focus on wastewater treatment applications within sewage sludge systems. Acknowledging the critical importance of cavitation analysis in sludge flow, we utilized OpenFOAM software and enhanced the default solver by integrating a concentration equation to improve simulation accuracy. Our investigation centered on the behavior of cavitation vortices near the pressure and suction sides of the pump blades to deepen the understanding of the underlying physics. To track vortex development, ten monitoring points were strategically placed along the flow channel, supplemented by a sampling line at the center of the pressure side to observe vortex dynamics. The results indicate that dense sludge fluids promote a higher density of cavitation vortices near the suction side. To further investigate these vortices, we applied three distinct mass flow rates (Q), each defined as a function of the designed mass flow rate (Q<sub>d</sub>). A key finding is that at the trailing edge under a flow rate of Q = 1.1Q<sub>d</sub>, the cavitation vortex assumes a larger, planar shape, extending across a significant portion of the outlet volute. This disrupts mass flow and reduces overall pump efficiency. Furthermore, the pronounced planar characteristics of the vortices at this flow rate are likely to generate increased operational noise. To quantify these phenomena, we developed a Mobility Index (MI). The MI indicates a 30–50% increase in vortex activity in sewage sludge flows and reveals a progressive occupation of vortices along pressure-side regions. Additionally, an increase in cavitation numbers resulted in a reduced MI value for both pure water and sewage sludge. However, the MI for sewage sludge remained approximately 35% higher than that of pure water, a difference attributable to the Brownian motion of suspended particles. This work introduces new criteria for cavitation analysis, providing a valuable framework for future research in this field.</p>

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Vortex cavitation behavior near suction and pressure surfaces of centrifugal pump blades in sewerage systems

  • 期刊论文

  • 发表日期：

    2026年2月11日

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  • Ali Najim Abdullah Saieed,
  • Mohammad Taghi Shervani-Tabar,
  • Moharram Jafari

摘要

This study investigates the fluid dynamics of cavitation vortices in centrifugal pumps, with a specific focus on wastewater treatment applications within sewage sludge systems. Acknowledging the critical importance of cavitation analysis in sludge flow, we utilized OpenFOAM software and enhanced the default solver by integrating a concentration equation to improve simulation accuracy. Our investigation centered on the behavior of cavitation vortices near the pressure and suction sides of the pump blades to deepen the understanding of the underlying physics. To track vortex development, ten monitoring points were strategically placed along the flow channel, supplemented by a sampling line at the center of the pressure side to observe vortex dynamics. The results indicate that dense sludge fluids promote a higher density of cavitation vortices near the suction side. To further investigate these vortices, we applied three distinct mass flow rates (Q), each defined as a function of the designed mass flow rate (Qd). A key finding is that at the trailing edge under a flow rate of Q = 1.1Qd, the cavitation vortex assumes a larger, planar shape, extending across a significant portion of the outlet volute. This disrupts mass flow and reduces overall pump efficiency. Furthermore, the pronounced planar characteristics of the vortices at this flow rate are likely to generate increased operational noise. To quantify these phenomena, we developed a Mobility Index (MI). The MI indicates a 30–50% increase in vortex activity in sewage sludge flows and reveals a progressive occupation of vortices along pressure-side regions. Additionally, an increase in cavitation numbers resulted in a reduced MI value for both pure water and sewage sludge. However, the MI for sewage sludge remained approximately 35% higher than that of pure water, a difference attributable to the Brownian motion of suspended particles. This work introduces new criteria for cavitation analysis, providing a valuable framework for future research in this field.