NUMERICAL STUDY OF FLOW PARAMETERS IN THE HIGH-HEAD FRANCIS TURBINE

The scientific exploration of numerical computation regarding spatial flow within hydraulic machinery components is examined. A survey of contemporary software systems is conducted, and the benefits of their utilization over experimental studies are evaluated. It is indicated that the optimal approach involves a blend of experimental investigations and numerical simulation. This methodology facilitates the validation of simulation outcomes under real-world conditions and iteratively enhances the model based on acquired data. A review of the widely utilized Ansys software program is provided, emphasizing its pivotal features and capabilities for analyzing flow components of hydraulic turbines. An algorithm for computing flow parameters in hydraulic turbines using the Ansys software suite is outlined. The subject of this study is the high-head Francis hydraulic turbine Fr 500. The turbine's geometry was constructed employing a sector-based approach. This technique allows for significant simplification of calculations within the computational fluid dynamics framework, thereby reducing computational workload while preserving result accuracy. In selecting mathematical and turbulence models, a comprehensive analysis of the problem was undertaken, identifying models most suitable for the specific situation to ensure dependable numerical simulation outcomes. For spatial flow calculations in the turbine's flow component, the standard k-ε turbulence model was adopted. Considerable attention was devoted to mesh generation, as mesh quality strongly influences result accuracy and reliability. An unstructured mesh comprising tetrahedral-shaped cells was employed for discretizing the flow component, with local mesh refinement at the edges of the runner blades and guide vanes. As a result of numerical computations, the values of primary flow parameters for the design operating mode were determined. A visualization of the flow within the flow component is provided, alongside the assessment of hydraulic losses and turbine efficiency. The efficiency values obtained differ from corresponding experimental values by no more than 1 %. A thorough examination of the flow structure within the flow path was conducted, yielding recommendations for adjusting the blade angle β1 to reduce inlet impact losses.