Determination of the main parameters of the pump-turbine using the block-hierarchical approach

This paper considers the application of the block-hierarchical approach to the study of the working process of the water passage of a radial-axial reversible hydraulic machine based on mathematical modeling. The advantages and features of this approach on the system of multilevel description of the working process are determined. It has been determined that the choice of the most effective model is influenced by the design stage of the water passage and the tasks that are set before designer. The general structure of the mathematical description using dimensionless coefficients for the turbine and pumping modes of operation of a reversible hydraulic machine is presented as a block diagram. Calculations of the main parameters of the pump-turbine for a head of 200 m were carried out. The kinematic characteristics (flow angles of the blade system) in the turbine mode and the hydraulic efficiency in the pumping and turbine modes were determined during these calculations. The mathematical model was applied to the kinematic description of the working process during determining the flow angels. According to the calculation results, the isolines of the angles at the optimal point have acceptable values. The values of the hydraulic efficiency at the optimal point of operation in pumping and turbine modes, obtained as a result of calculations, showed good convergence with the experimental data (0.1 % and 0.7 %, respectively). This indicates the correctness of the calculations performed using this approach.