New Research


2008/08/01

Flow Induced Vibration in a Steam Control Valve for Power Plants


Professor Yoshinobu Tsujimoto , Assistant Professor Koichi Yonezawa

In thermal and nuclear power plants, electric power is generated with steam turbines, which are driven by steam with high pressure and high temperature. A steam control valve is used in order to control the steam flow from a steam generator and the steam turbine.
During the startup and shutdown transient of the power plant, the steam control valve restricts the steam flow in order to change the operational condition of the steam turbine slowly. Under such conditions, the pressure difference between upstream and downstream of the valve is so high that the flow velocity of the steam becomes supersonic. In the super sonic jet, shockwaves occur and they may cause pressure fluctuations of the pipeline systems and the valve. Such a situation is one of the problems that reduce the reliability of the power plant.

Our research team is carrying out the experimental and numerical investigations of the flow in the steam control valve and its downstream pipe. The figure shows the Mach number distribution around the valve. Several shockwaves are observed. Under such flow patterns, the flow is unsteady and cause large loads on the valve head. Additionally, the flow disturbance cause pressure waves and results in the acoustic resonance in the downstream pipe.


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