Check Valve Flow and Disk Lift Simulation Using CFD

Computational Fluid Dynamics (CFD) is increasingly being used as a reliable method for determining flow characteristics of a wide range of flow situations. This paper presents an investigation on the application of CFD to characterize the opening and closing of check valves. Specifically, using CFD results, a procedure was developed to determine valve flow coefficients (C_V) as a function of disk lift positions as well as to determine the flow rate required to achieve full open or predict intermediate disk lift positions. The method could be used for a wide range of check valves such as swing check valves, lift check valves, tilting disk check valves, or inline check valves. Using CFX which is a part of the ANSYS suite of finite element programs, examples of the predictive nature of CFD to characterize check valve performance are presented to address swing check and lift check valve designs. It is shown that balancing flow-induced forces on the disk and considering the disk assembly weight in the process is sufficient to model the valve lift behavior. Analysis results from this approach were compared with available test data of the modeled valves. The comparison showed good agreement, thus validating that both flow coefficients (C_V) and flow rates across the valves at different disk lift positions can be reasonably predicted with this approach. The results of this study suggest that this approach can be used for valve design optimization and flow analysis of check valves. However, it should be pointed out that CFD is an evolving technology and is not a substitute for testing. The use of this tool compliments testing and, if carefully managed, can save valve development cost.