Experimental investigation of the effects of hydrophobic surfaces on cavitation performance of a centrifugal pumps

Centrifugal pumps are the most common used hydraulic machines in the industry. Cavitation in centrifugal pumps causes a significant reduction in the working life of the pump, as well as a decrease in capacity, performance in addition to causing noise and vibration. Thus, cavitation should be avoided and operating conditions and design also have an impact on cavitation performance. In this study, the wet surfaces of the impeller were coated with a composite solution to gain hydrophobic properties in order to prevent cavitation without changing the design of a centrifugal type pump. Three different composite surface coating solutions were prepared by reinforcing the fluorinated ethylene propylene (FEP) coating material with 3% by mass of graphite (FEP-C), graphene (FEP-G) and hexagonal boron-nitride (FEP-HB) and their hydrophobicity was determined by measuring with contact angles of 120°, 124°, 133° respectively. The cavitation performance has been experimentally tested on NPSH and Thoma cavitation parameters before and after the impellers are coated. It was determined that the NPSH values of the FEP-C, FEP-G and FEP-HB coated pump impeller increased by %6.15, %6.96, %10.72(respectively) compared to the uncoated impeller. And the Thoma cavitation parameters increased by %10.16, %12.9, %18.09(respectively) compared to the uncoated impeller.