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Coherent Structures in Pump-Intake Flows: A Large Eddy Simulation (LES) Study

Author(s): Talia Tokyay; George Constantinescu

Linked Author(s): George Constantinescu

Keywords: Water pump intakes; Large eddy simulation; Unsteady vortices

Abstract: The presence of unsteady intermittent meandering wall attached and free-surface vortices is a common feature of pump intake flows. These vortices are known to induce high levels of unsteady swirl inside the pump column and negatively affect the performance of the pumps. In the present study we describe the use of a LES model to numerically study the flow and main coherent structures. The numerical engine is a non-dissipative Navier-Stokes massively parallel solver [4] that can use hybrid unstructured grids. The model is first validated using the PIV data collected on a scaled model of a pressurized (no free surface) pump sump. It is found that most of the main vortical structures are changing considerably their structure and intensity in time. The flow is dominated by large scale interactions among these vortices. For the given flow conditions the main vortex in the flow originates at the floor. It is found that this vortex is responsible for most of the circulation inside the pump column. This study shows that LES can be used to obtain detailed information on the evolution and interactions among the main vortices that is very hard to obtain from scaled model studies. Moreover, this CFD tool can be used to test new design ideas or to optimize the shape of various vortex suppressing devices.


Year: 2005

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