- Francis turbines are radial flow turbines used in hydroelectric power generation. They have adjustable guide vanes and runners that control water flow. - Key dimensions include the diameters and widths at the inlet and outlet, as well as the rotational speed. These dimensions are calculated based on design criteria like flow rate, head, and hydraulic efficiency. - Dimensions are chosen to satisfy requirements for net positive suction head (NPSH) and minimize hydraulic losses while maintaining high hydraulic efficiency.