Author(s): Stephane Etienne

Linked Author(s):

Keywords: Aerating turbines; Two-phase flow; Dissolved oxygen; Experimental setup;

Abstract: Oxygenation of water downstream of hydroelectric turbines is of great importance for the preservation of the ecosystem downstream the dams. The admission of air into the low-pressure zones close to the turbine can be used to restore dissolved oxygen in poor quality water. In this context, the National Research Council of Canada (NSERC) and General Electric initiated an industrial research Chair in two-phase flow based on an experimental approach to characterize aerating flows similar to those found in hydroelectric facilities. Experimental measurements will focus on the quality and extent of bubbles populations. Indeed, the size of the bubbles and the extent of the cloud of bubbles influence the effectiveness of an aerating system. A new laboratory named Laboratory for Experiment with Great Height (LEGH) has been built to carry out this mission. The experiments can be conducted by independently varying the pressure and velocity close to the typical operating conditions of a turbine. The experiments will result in the creation of a validation database for multiphase flow simulation programs and enrich the knowledge of the behaviour of two-phase flows. This paper describes the design and operation of this new test loop. A vacuum pump will allow to set the pressure level in the loop down to 0.03 bar, which is essential to assess independently the effect of Froude (flow velocity), Thoma (pressure level) and Reynolds (viscosity) numbers. Thanks to a 300 hp pump, the loop is able to reach a 2000 m3/h flow rate corresponding to a velocity of 25 m/s inside the test section. The loop operates with an air injection system. The injected air is removed by an air water separator before the flow returns to the pump. The loop is built on three floors, to reach near cavitation pressures on the third floor (where the test section is located) and avoid cavitation pressure on the first floor where the pump is installed.

DOI: https://doi.org/10.3850/38WC092019-1238

Year: 2019