“…It has been reported that the flow pattern around the valve is a transonic and separated jet, and as a result, mass flow fluctuations with large pressure fluctuation occurs as described by Widel [1], Araki et al [2] and Zhang and Engeda [3], Zhang et al [4], Morita et al [5], Morita et al [6], Yonezawa et al [7] and Yonezawa et al [8]. As a result steam turbine control valves are known to be a source of noise and vibration.…”