Author(s): Gerd Demny; Katja Rettemeier; Christian Forkel; Jurgen Kongeter
Linked Author(s): Jürgen Köngeter
Keywords: Numerical Modelling; Large-Eddy Simulation; Finite-Element Method; 3D-Velocity measurements; ADCP; Validation; Hydraulic Structures; Run-of-River Power Plant
Abstract: Especially the intakes of run-of-the-river power plants are very complex engineering buildings. The application of a finite element code, which calculates the threedimensional, transient, and turbulent flow, arise the possibility to investigate all flow phenomena in the intake area in detail. After numerous verification examples, the intake of the run-of-river power plant Wintrich at the river Moselle was selected for the validation as a real hydraulic engineering problem. The three dimensional finite element grid of the intake cove contains one third of the weir, the separation pier and the bulb turbine power plant with four intake chambers. The grid counts 40. 105nodes and 34. 584 elements. Even though the numerical grid is fairly rough, a Large Eddy turbulence approach is applied with a Smagorinsky subgrid scale model for the medium scale eddies. The smallest scales are accounted for with a constant background eddy-viscosity. The dimension of the grid allows reasonable calculation time while all significant current structures can be modelled. An accustic-dopplercurrent-profiler (ADCP) and a hydrometric-current-meter were used to obtain verification data. The measurements were taken in various places within the weir and the intake cove. The ADCP measurements and the current meter data provides high quality data for a detailed validation of the model. The comparison between simulated and measured velocity vectors in different investigated spots shows very good results. The simulations show, that the geometry of the intake building has an important influence on the quality of the inflow. The presented results indicate a distinct vortex shedding at the separation pier. The extension of the separation zone is non-steady and fully three-dimensional. A large dead water zone in front of the weir causes a pulsing flow around the separation pier and an oblique inflow into the turbines.
Year: 1999