Numerical Study on Cavitation Occurrence in Globe Valve

Abstract

Cavitation in a valve leads to trouble and inconvenience for factories. Valves in a piping system are ruined, leading to costly replacements every several months. To reduce the cost caused by cavitation in a valve, a cage is utilized to make cavitation occur only in the region adjacent to the cage itself; therefore, only the cage needs to be replaced. To validate the design of a cage, simulation of the turbulent flow field inside a globe valve and the occurrence of cavitation are necessary for a valve designer. To reach this purpose, prediction of the cavitation inside the globe valve with and without a cage is undertaken, and a cavitation model is established in this study. The percentage of vapors in each computational cell is calculated using the proposed cavitation model. Two various cages, the one-stage perforated cage and the one-stage step cage, are considered. Vapor resulting from cavitation appears in the vortices existing inside the valve and at the downstream region of the globe valve without a cage. Nevertheless, vapor does not occur in those regions in the globe valve with those two cages; in other words, cavitation inside the globe valve primarily occurs in the vicinity of the cages. In the valve body and downstream region, ruin from cavitation is prevented when those two cages are installed in the globe valve. In addition to the globe valve, the proposed cavitation model can be applied to prediction of cavitation in other control valves.