Hydraulic Performance of a New Isokinetic Turbine for Rivers and Artificial Channels

Vlad Hasmatuchi, Sébastien Alligné, Jean-Louis Kueny, Cécile Münch

Thursday 2 july 2015

11:15 - 11:30h at South America (level 0)

Themes: (T) Water engineering, (ST) Hydraulic machinery and industrial flows

Parallel session: 11C. Engineering - Industrial

A new ducted isokinetic turbine for rivers and artificial channels has been designed. The new (patented) concept consists on an axial turbine with two joined concentric runners: an annular turbine runner and a central pump runner. The aim of the pump runner is to induce a suction effect in the central area in order to increase the axial velocity passing through the turbine runner and consequently the hydraulic efficiency. In a first step, steady incompressible monophasic turbulent flow (k-_ model) numerical simulations have been used to optimise the hydraulic profile of a turbine with an expected mechanical power of 1 kW. A reduced computational domain including only a periodic quart of the turbine (at prototype scale) immerged in a water box has been considered. The Fine/Turbo package of the Numeca commercial code has been employed to solve the RANS equations using the finite volume method. Then, numerical simulations of unsteady incompressible homogeneous multiphase turbulent flow (using the SST model) have been performed on a computational domain including the full water passage of the final prototype, placed in a in a run-of-river tailrace canal with trapezoidal cross-section, to recover its hydraulic efficiency. The URANS equations have been solved with the Ansys CFX 15.0 commercial code using the finite volume method. The main contribution of this work consists on a successful implementation of the numerical tools to optimise and to recover the hydraulic efficiency of a new isokinetic turbine with and without the free-surface effects taken into account. Moreover, the effect of the pump runner is assessed by comparing the obtained efficiency with performances of the isokinetic turbine featuring a free central open passage.