A Study of Flow Oscillation on the Steam Control Valve (2nd Report, CFD Approach)

A steam control valve causes vibration of the piping when the opening is in the middle condition. For the rationalization of maintenance and management in the plant, the valve should he improved, but it is difficult to understand the flow characteristics in detail by experiment because the flow around the valve is complex 3D stlacture and becomes supersonic (M>1). In this report, a high-precision 3D CFD code for compressible flow is developed. After validating the code by comparing with experiments, the detailed flow characteristics around the valve are studied. At only the middle opening condition, a circumferentially propagating spike-type pressure fluctuation caused by asymmetric flow around valve can be seen. As this fluctuation causes cyclic side load on the valve body, it is thought to be the cause of vibration.