The International Association for Hydro-Environment Engineering and Research (IAHR), founded in 1935, is a worldwide independent organisation of engineers and water specialists working in fields related to the hydro-environmental sciences and their practical application. The 28th IAHR Symposium on Hydraulic Machinery and Systems took place in Grenoble on July. More than 300 delegates, from 32 countries, were present. And a total of 183 papers were presented during the conference. The latest developments regarding the computational techniques in Hydro were presented, such as the new design tools. The behaviour of the hydraulic installations during transients and their interactions with the electrical grid was also on the main point of interest.
The article “CFD Investigation of Complex Phenomena in S-Shape Region of Reversible Pump-Turbine”, submitted by Clement Jacquet was presented during the opening session and was well received by the hydraulic community. This article focuses on the numerical simulation of pump-turbines operating at off-design condition using a hybrid RANS/LES approach. Pumped Storage Plants (PSP) using reversible pump-turbines are often looked at as one of the most economically viable way to provide stability and flexibility to the electricity grid. Although, the existing technology of pump-turbines needs to be adapted in order to respond the new need of the electrical grid for stabilization, due to the integration to the grid of intermittent renewable energy sources. One of the most important challenges is to improve start-up and shutdown procedures. For reversible high head pump-turbines, the characteristic curves exhibit an S-shape in the turbine quadrant. This S-shape leads to unstable behaviour of the turbine when coupling to the grid or during load rejection at maximum output. Typically the piping system can be exposed to severe pressure oscillations. The presented paper highlights the evolution of the flow behaviour for a large range of operating conditions: from the optimal efficiency point to the zero discharge condition. In that range the flow inside the pump-turbine is characterized by unsteady complex hydrodynamic phenomena. These phenomena require deep investigations to improve the behaviour of the pump-turbine in such operating conditions. Thanks to these results the program P5 can bring new ways of designing turbines. Joint effort between P1 and P5 will allow the integration of hydraulic limits within the electrical grid simulation tool.