Effect of labyrinth cavities on cavitation reduction in a conical valve

High-intensity cavitation occurring in water flow past a valve causes vibration, noise, fatigue, and erosion of the valve and the associated piping. This paper aims to reduce cavitation through a design modification on the tapering body of a conical valve. The flow and cavitation characteristics of two different 1 in sized hydraulic conical valves have been investigated. The first one is a conventional conical valve (CCV). The newly designed second valve has labyrinth cavities on the conical valve body and hence is named the labyrinth conical valve (LCV). Computational fluid dynamics (CFD) simulations identified LCV to cavitate less than CCV. To validate the CFD predictions, different experiments were conducted. The predicted mass flow rates were found to be in close agreement with the experimental results. The bubble flow patterns of the valves were indistinguishable in visual observation. Hence, a detailed digital image processing (DIP) analysis was invoked. It showed that the cavitating flow through a LCV possessed both less bubble pixel count and bubble image entropy attributable to low cavitation. Further endorsement was obtained through a bacterial testing method using the interesting fact that cavitation can disinfect water. This test indicated that the number of E. coli bacterial colonies in the water handled by a LCV is larger compared to that of a CCV, thus confirming that the LCV is a low-cavitation valve. © 2008 Begell House, Inc.