Modeling and numerical simulation of hydro power flows

Abstract: This work is about high precision numerical water flow simulations of hydro power related applications, and especially draft tube flows. Because of the accuracy requirements for these types of simulations (the efficiency of a hydro power turbine can be over 90%), the work has been devided into several steps; verification, validation and modeling. Verification or solving the equations right is about estimation of iterative and grid errors in CFD (Computational Fluid Dynamics). Validation or solving the right equations (and modeling) has included investigation of a turbulence model, an averaging technique for the flow field in the runner and transient RANS simulations. To summarize: It is today possible to simulate the flow in separate parts of a complete hydro power plant with high accurary. To accomplish this it is necessary to have control of the numerical model; i.e. grid, boundary conditions, numerical errors, etc.