Abstract
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 cause of vibration should be clarified and the valve should be improved. In current research, we found a valve-attached flow occurs and causes a quasi-periodic spike-type pressure fluctuation at only the middle opening condition in rigid support condition. As this fluctuation causes cyclic side load on the valve body, it is thought to be the cause of vibration. But we don't know the effects of flow-induced vibration when this pressure fluctuation interacts valve vibration because this phenomenon has complex flow structure and the flow is supersonic. This report describes the effect of flow-induced vibration to the flow around the valve. We conducted some experiments with an elastic support, and followings are found. In specific lift range, a resonance between valve and rock-in phenomenon, which the quasi-periodic pressure fluctuation is drawn in a natural frequency of the valve and becomes periodic, occurs. In addition, a damping ratio of the valve decreases and the amplitude has grown in the range.
