Session: 8.3.2 - Pumping Machinery II

Paper Number: 158773

158773 - The Effect of Wear Gap on Cavitation Behavior in Sewage Pump One Channel Impeller 

Abstract: 

Cavitation is a significant concern in sewage pumps, as it impacts both performance and efficiency. This study investigates how different wear gap configurations of axial and radial gaps affect cavitation behavior and pump operation. To achieve this, two distinct wear rings were designed for the same pump housing and impeller to differentiate the effects of varying the gap geometry on cavitation, with a particular focus on visual measurements. One channel impeller was used for the investigations,The impeller was modified by drawing mesh lines of 5 mm² as a reference background for the cavitation cloud, helping to define cavitation inception. Additionally, the impeller was painted to enhance the visibility of the cavitation inception. The experiments were conducted using a centrifugal pump, connected to a closed-loop test setup, The setup consisted of a 2m³ tank, DN 100-200 pipelines, and a vacuum pump to control the pressure in the suction line. Moreover, pressure and temperature sensors, as well as a LabVIEW code, were specially designed to collect the measuring points. This test rig allowed for the measurement of NPSH_3% and NPSH_ic values at 11 different flow rates, offering a wide range of operating conditions. Cavitation inception was observed using a high-speed camera, endoscope, and LED lighting unit, this unit was specially designed and manufactured for that purpose.
 

The results showed that the radial gap configuration required higher NPSH_3% values at higher flow rates compared to the axial gap configuration. At very low flow rates, specifically at 0.2 Q_opt, both gap configurations exhibited nearly identical performance. However, as the flow rate increased, the radial gap configuration showed a noticeable increase in NPSH values, signaling greater resistance to cavitation. Furthermore, cavitation inception was observed at higher values for the radial gap configuration, meaning that cavitation initiated at higher suction head values compared to the axial gap configuration. At higher flow rates, the wear ring with the radial gap also displayed less resistance to cavitation initiation, suggesting that the radial gap configuration may be more prone to cavitation under certain conditions.

These findings indicate that the wear gap configuration plays a role in cavitation behavior and could influence the design of more efficient sewage pumps. The research highlights the importance of understanding the effects of wear gaps on cavitation, providing valuable insights for optimizing pump design to reduce cavitation-related issues. This study also addresses a gap in the existing literature, as there is limited research on the specific effects of wear gap configurations on cavitation in pump systems, the study shows a different fluid behavior when changing only one factor which is the wear gap, this will help solving practical problems in industry sector. This research adds knowledge that could guide future pump design improvements aimed at enhancing performance and reliability in sewage pump systems.

Presenting Author: Samer Mekhael Technical University of Berlin

Presenting Author Biography: Samer Mekhael is a Research Assistant with a Master's degree in Water Engineering and is currently pursuing a Ph.D. in Fluid Dynamics at Technical university of berlin. With a background in Mechanical Engineering, his research focuses on understanding fluid dynamics, particularly in the context of cavitation behavior in sewage pumps. His current paper, "The Effect of Wear Gap on Cavitation Behavior in Sewage Pumps - One Channel Impeller," explores how different wear gap configurations affect pump performance.

Samer has also published a paper in the ASME journal titled "Cavitation Behavior in Sewage Pumps," focusing on pump dynamics and cavitation issues in sewage systems. He aims to deepen the understanding of cavitation and its implications on different pump impeller, ultimately optimizing sewage pump performance and reliability. His work aims to fill the gap between theoretical fluid dynamics and industry, providing investigations that help understanding flow in centrifugal pumps and cavitation-related issues.