We have the pleasure to present two papers from the ALPHEUS Project (Chalmers University of Technology) at the AHR 31st Symposium on Hydraulic Machinery and Systems. The 31st symposium provides unique opportunity to the academic and industrial research teams to exchange the stat-of-the-art knowledge and ideas that will help to develop the next-generation of hydropower technology.
The event will be held atNTNU, Norway, from the 26th of June to the 1st of July. The papers will be published in the IOP Conference Series: Earth and Environmental Science after the conference.
The first paper, ‘Evaluation of Startup Time for a Model Counter-Rotating Pump-Turbine in Pump-Mode’, is the investigation of the impact of startup time in pump-mode for an unfavourable startup scheme with CFD.
Asbtract: A larger part of the electricity is today from intermittent renewable sources ofenergy. However, the energy production from such sources varies in time. Energy storage isone solution to compensate for this variation. Today pumped hydro storage (PHS) is the mostcommon form of energy storage. Usually, it requires a large head, which limits where it can bebuilt. In the EU project ALPHEUS, PHS technologies for low- to ultra-low heads are explored.One of the concepts is a counter-rotating pump-turbine (CRPT). The behaviour of this designat time-varying load conditions is today scarce. In the present work, the impact of the startuptime for a CRPT is analysed through computational fluid dynamics (CFD) simulations. Theanalysis includes a comparison between a coarse and a fine CFD model. The coarse modelproduces acceptable results and is 50 times cheaper, this model is thus used to assess the startuptime. It is found that longer startup times generate lesser loads and peak values. A startuptime of 10 s may be a sufficient alternative as the peak loads are heavily reduced compared tofaster startups. Furthermore, there is not much difference between a startup time of 20–30 s.
Authors: Jonathan Fahlbeck, Hakan Nilsson and Saeed Salehi from Department of Mechanics and Maritime Sciences, Chalmers University of Technology.
The second paper, ‘Development of Blade Element Momentum (BEM) Method for Hydropower’, concerns the newsly developed BEM method for a CRPT at Chalmers University.
Abstract: The BEM method is extensively used for analyzing the aerodynamic performanceof wind turbines and marine propellers. It is computationally fast and is easily implementedwhile it can give fairly accurate results. Application of the BEM method to predict the forcesacting on rotor blades for a model scale axial shaft-driven Counter-Rotating Pump-Turbine(CRPT) is investigated. Some modifications have been proposed to adopt the classical BEMmethod for CRPT machine and the results are validated against results from ComputationalFluid Dynamics (CFD). The results display that the proposed modifications can improve theloading predicted by BEM. However, the improvements are more pronounced in pump moderather than turbine mode.
Authors: Hamidreza Abedi, Cristobal Ibanez Uribe, Jonathan Fahlbeck and Hakan Nilsson from Department of Mechanics and Maritime Sciences, Chalmers University of Technology.