Ejection effect in a low-head hydropower plant: turbine power and efficiency

The aim of this research is to complement and improve the results about ejection effect in a low-head hydropower plant from a previous study in physical models and to evaluate the effect of ejection on the turbine power and efficiency, in the model alternative with the best performance. The study covers four additional geometric alternatives, aside from the original design and the six already tested alternatives in that study, using 1:70 scale model tests. Three approaches were considered: (1) The development of a theoretical equation for the ejection effect, based on the equations of conservation of momentum and energy, (2) An assessment of an empirical relationship for the effective ejection using dimensionless flow parameters from 521 flow scenarios and (3) The development of two empirical relationships between the effective ejection and the power and efficiency increments of the HPP turbines (63 flow scenarios).