Effects of Cavitation Damage on the Hydraulic Characteristics of a Gate Valve

This paper explores the effects of cavitation damage on the hydraulic performance of a gate valve. Cavitation is the phenomenon in which a fluid evaporates to form vapor bubbles which then subsequently implode. A Computational Fluid Dynamics (CFD) model of water flowing through a partially opened 1 inch (2.54 cm diameter) gate valve was developed using Unigraphics NX 7.5. NX 7.5 utilizes a k-ε turbulent flow 2-equation model. The low pressure and high velocity regions were identified in the CFD model to predict the location of the cavitation site in the valve. In order to simulate the effects of ageing due to cavitation, a gate valve was mechanically damaged in different stages. Damaged and undamaged valves were then inserted in a hydraulic test loop to observe the flow rate and pressure drop across the valves. The valves’ hydraulic loss coefficient was then calculated and compared. The cavitation index of the damaged and the undamaged gate valves was also calculated to predict the likelihood of cavitation. The results show that the aged valve had lower loss coefficients at the corresponding opening positions compared to the ones for the non-aged valve. Also, it was observed that the aged gate valve had less likelihood of cavitation compared to the non-aged gate valve.Copyright © 2013 by ASME