Pressure fluctuation of steam on the disc in a triple eccentric butterfly valve

Abstract

The triple eccentric butterfly valve has an excellent structure for sealing fluid and can also produce additional torque to assist in opening or closing the valve. However, flow separation and vortex shedding often occur because of the rugged surface of the valve disc. Pressure fluctuation on the disc induces vibration and can severely damage the valve and pipeline. To investigate the pressure fluctuations due to steam, the CFD method is used to simulate the 3D unsteady flow inside the valve and to obtain the transient pressure and velocity at key points in the five typical sections in the fully open state. The discrete Fourier transform method is adopted to analyze the spectrum parameters. The Strouhal numbers for vortex shedding are also obtained. Finally, an experimental modal analysis is conducted to test the natural frequency of the disc–stem assembly. The tested natural frequency is much higher than the highest steam pressure fluctuation frequency in the case of the maximum flow rate. Moreover, pressure fluctuations caused by fluid force do not induce resonance of the disc–stem assembly and there no lock-in phenomenon occurs.