Investigation of a francis turbine performance using cfd and site efficiency measurements

The mechanical energy is converted into electrical energy with the help of a generator, after converting the energy of the flowing water into mechanical energy with the help of a hydraulic türbine in hyrdoelectric power plants. The turbine type that is mostly used is Francis type turbines. The runner with its complex blade geomerty is the most important part of Francis turbines. The runner blades have a rotating and variable three-dimensional profile to direct the water and provide desired performance. The complicated runner blade profile and the fact that these profiles are confidential information of companies, restrict access to these profiles. The full geometry of the runner cannot be obtained from technical drawing data. Therefore, in rehabilitation works to be carried out in hydroelectric power plants, the existing runner is reverse engineered with the help of laser scanning. In addition, after obtaining geometry, blade design variables such as meridional profile, distribution of blade angles and blade thickness distribution should be obtained. After these parameters are acquired, verification analysis should also be made with Computational Fluid Dynamics (CFD) with the blade structure that was formed. In this thesis, in Altınkaya Hydroelectric Power Plant, turbine parts are scanned in the field with the help of laser scanning, obtaining a 3D point cloud. Forming solid models from this point cloud, creating the mathematical model of the runner and other parts, making steady and unsteady CFD analysis of the whole turbine, with the Hill chart diagram are the other parts of the process utilized in this work. Site efficiency measurements were made, and these measurements were compared with the results obtained by the Computational Fluid Dynamics (CFD) method. The Hill chart obtained by numerical methods were compared with site measurements.