Author(s): Frank Suerich-Gulick; Susan. J. Gaskin; Marc Villeneuve; Étienne Parkinson

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Keywords: Axial vortex stretching; hydraulic model; hydraulics of renewable energy systems; hydropower intake; particle tracking velocimetry; turbulence in rotating flow; vortex dynamics

Abstract: Axially stretched free-surface vortices occur at low-head hydropower intakes under specific flow and geometric conditions. When they are sufficiently strong, they can harm performance or cause premature failure of mechanical components such as turbine blades or guide vanes. Laboratory-scale experimental models are currently used to assess the risk of vortex formation during the design phase, but uncertainty remains as to how vortex characteristics translate from the laboratory scale to the much larger scale of an actual hydropower plant. This paper proposes a semi-empirical model that roughly predicts how the approach flow and intake geometry determine the key vortex characteristics (the core radius, bulk circulation and the depth of the free surface depression). The model is developed using detailed velocity measurements of the approach flow and the flow inside the vortex in a laboratory-scale physical model, using analytical models and insights drawn from previous work.

DOI: https://doi.org/10.1080/00221686.2014.896425

Year: 2014