A Gradually Diverging-converging Pipe for the Reduction of Aerodynamic Torque of Butterfly Valve Plate

When the butterfly valve installed in the straight pipe is opened, vortex will be generated downstream of the valve plate, which will cause pipe vibration and consequently affect the aerodynamic torque characteristic of the valve. In order to reduce the impact of vortex, a pipe with a gradually diverging-converging structure is added near the butterfly valve outlet. Taking air as the flow medium, the flow fields with the valve plate motion are simulated by means of CFD software and its dynamic mesh technology. The distributions of velocity and pressure in the pipeline during the dynamic process of the opening of the valve plate are analyzed and the aerodynamic torque characteristic of valve plate is gotten meantime. The results show that: 1) the vortex intensity can be effectively reduced by the installation of the gradually diverging-converging pipe near the butterfly valve outlet; 2) the aerodynamic torque of the valve plate is obviously reduced by 32% and the accurate control of the flow rate of the valve becomes easy.