A CFD study of the flow field, resultant force, and aerodynamic torque on a symmetric disk butterfly valve in a compressible fluid

Butterfly valve performance coefficients are necessary for predicting the required torque necessary to operate the valve along with other essential parameters necessary for ensuring the safe operation. The availability of performance coefficients for compressible flow is limited, and experimental testing can be cost prohibitive. The capability of using computational fluid dynamics is a test to determine its viability for determining performance coefficients. The flow field, resultant force, and aerodynamic torque on a symmetric disk butterfly valve are studied computationally at disk positions 45 deg and 70 deg over a range of operating pressures. The range of pressure ratios was chosen to include subsonic and supersonic flow states. The flow fields were predicted using the k-epsilon renormalization group theory (RNG) turbulence model. The computational results were obtained using CFX 10 and were performed on an SGI ALTIX 330. The flow field is illustrated using velocity contours colored by a Mach number, and the effects of the disk position and pressure ratio are illustrated using disk pressure profiles. The computational predictions for the aerodynamic torque coefficients are compared to test data at both 45 deg and 70 deg. A simplistic model used to predict the resultant force acting on the disk is compared against the computational results to obtain a better understanding of the resultant force trend throughout the stroke. The numerical results were generally in good agreement with test data, although a few disparities existed.