The paper refers to the numerical analysis of the internal flow in a hydraulic cross-flow turbine type Banki. A 3D-CFD steady state flow simulation has been performed using ANSYS CFX codes. The simulation includes nozzle, runner, shaft, and casing. The turbine has a specific speed of 63 (metric units), an outside runner diameter of 294 mm. Simulations were carried out using a water-air free surface model and k-εturbulence model. The objectives of this study were to analyze the velocity and pressure fields of the cross-flow within the runner and to characterize its performance for different runner speeds. Absolute flow velocity angles are obtained at runner entrance for simulations with and without the runner. Flow recirculation in the runner interblade passages and shocks of the internal cross-flow cause considerable hydraulic losses by which the efficiency of the turbine decreases significantly. The CFD simulations results were compared with experimental data and were consistent with global performance parameters.

A process that enables us to improve the design of 2D centrifugal and helico-centrifugal pumps is presented. First of all, the definition of the impeller geometry as well as the analysis of its global performances are carried out starting from the mean streamline method (1D), based at the same time on ideal models and experimental correlations. A second stage of optimisation is achieved from a quasi three-dimensional (Q3D) method, by studying the meridional flow and blade-to-blade flow. Finally, 3D flow solution is performed by CFD tools. Nowadays, we have a group of tools which help the designers improve the performance of new machines. These digital tools are built around two computer programs, HELIOX developed for design and performance analysis in any centrifugal and mixed flow pumps equipped with volute or deswirl vanes, and also the module REMIX that gathers the meridional flow analysis and the simplified blade-to-blade one. To validate this procedure, a centrifugal machine with a volute (NS32) was modified and studied with it, and the results were simultaneously compared with the previous trial runs and with the software CFX-BladeGEN+ and CFX-TASCflow. The results for a machine equipped with a deswirl (VM51) are also presented.