Study of a novel hydro turbine with ultra-small unit discharge in theoretical calculation and numerical simulation

A novel hydro turbine with the ultra-small unit discharge was suggested and studied for the first time. It was specially developed for hydraulic energy recovery with a smaller flow rate and medium available head, its highlight feature is straight blades in the radial direction. In this paper, the theoretical and numerical simulation of a novel hydro turbine was studied. First, with the working process and principles introduced, the theoretical models were established for the prediction of optimal unit speed, optimal unit discharge, and performance curves. Second, numerical simulation was carried out to study the performance of the novel turbine and verify the theoretical models. Different mesh quantity cases were investigated to select an accurate configuration. The numerical simulation predicted that optimal unit speed was 57.07 r/min, and optimal unit discharge was 0.0705 m 3 /s, while the specific speed was 42.3 m kW. Comparisons between theoretical calculation and numerical simulation show the accuracy of the theoretical models. Finally, a tail energy recovery runner was proposed to improve the performance of the novel turbine, and maximum efficiency was improved from 79.6% to 84.5%. The novel hydro turbine fills the blank working area between Pelton turbine and Francis turbine, and could be easily applied to engineering with low cost and simple manufacture.