CFD prediction of Von Kármán vortex shedding in Francis turbines- A case study

Mostly undesirable transient phenomena in Francis turbines are vortex shedding, pressure pulsations, and flow instabilities. Assessing each one of these phenomena conventionally was done by conducting model experiments which at times become costly and time consuming for several design alternatives in design optimization. Recently, computational fluid dynamics (CFD) has become an effective tool for predicting detailed flow information in turbine space.In this study, Fluent software, as a well-known CFD tool, was applied to predict flow parameters (i.e. velocity magnitude, turbulent kinetic energy, and turbulent Intensity) for different runner trailing edges of Francis turbines, by solving RANS equations with k-ε turbulence model. To aim this purpose, six different runner trailing edges are designed and five points are set as ‘fixed measuring points’ to report the flow parameters of each simulated case. The results show that the best case (i.e. SHAPE 2) is in good agreement with the in site experiments.

CFD prediction of Von Kármán vortex shedding in Francis turbines- A case study Keywords:

Vortex Shedding , Fluent , CFD , Flow Parameters