Preventing Noise Caused by Vortex Shedding In Gate Valves and OrHlces

Abstract

Gate valves and high-energy orifices can both act as sources of noise. This noise can represent a simple environmental problem or, in severe cases, can cause piping failures within hours. This paper presents the results of two studies, one to eliminate noise in the main steam lines of a new reactor, and, the other, to develop design guidelines for preventing noise in multi-stage, high-energy orifices. Both the valves and orifices were found to have a common noise generation mechanism, namely, an unstable fluid shear layer (e.g., vortex shedding) coupled with a fluid-resonant conditions (i.e., an acoustic resonance). The main steam line noise was found to be caused by periodic vortex shedding across the seat cavities of the main steam isolation valves. The orifice noise is thought to be due to vortex shedding within the orifice holes themselves. This paper reviews the findings of both studies and presents measures that can be taken to eliminate noise problems.