Rapid Close of a Butterfly Valve Placed in a Curved Channel: A Computational Study of Unsteady Steam Flow and Aerodynamic Torque

The transient steam flow inside a curved channel, which is embedded with dual butterfly valves (stop valve & throttle valve), was numerically simulated when the throttle valve was rapidly closed. Two cases with different closing time were particularly compared in terms of the instantaneously varying flow pattern and aerodynamic torque, i.e., 0.5 s and 1.0 s; as the benchmark cases, the flows at different opening angles of the valve disk were also simulated for comparison. To accurately capture the transient flow, a total of 30 meshes corresponding to different opening angles of the throttle valve’s disk were preliminarily built by using ANSYS ICEM CFD 14.0, while mesh deformation and remeshing methods were used as Dynamic Mesh model to get the consecutively updated mesh. The SST model was chosen as turbulence model and ANSYS CFX 14.0 Software Package was used to solve the flow field. The results showed that rapid close of the throttle valve would lead to an overall flow imbalance between the inlet and the outlet, which was deteriorated with the decrease in the closing time.