A numerical prediction of the hydrodynamic torque acting on a safety butterfly valve in a hydro-electric power scheme

A numerical study of the flow through a safety butterfly valve used in a hydro-electric power scheme to stop water supply to a downstream penstock is reported. Computational fluid dynamics applied in a quasi-steady manner is used to predict the variation in hydrodynamic torque coefficient with opening angle during a constant head test. Factors influencing these results, such as Reynolds number and unsteady flow effects, are found to be significant. The predicted results are compared with field measurements of the full-size valve. Issues associated with applying the numerical results to predict valve characteristics at higher Reynolds numbers are discussed. Further computational and experimental studies are recommended.