Numerical analysis of an initial design of a counter-rotating pump-turbine

Abstract

Renewable sources of energy are on the rise and will continue to increase the coming decades [1]. A common problem with the renewable energy sources is that they rely on effects which cannot be controlled, for instance the strength of the wind or the intensity of the sunlight. The ALPHEUS Horizon 2020 EU project has the aim to develop a low-head hydraulic pump-turbine which can work as a grid stabilising unit. This work presents numerical results of an initial hub-driven counter-rotating pump-turbine design within ALPHEUS. Computational fluid dynamics simulations are carried out in both prototype and model scale, for pump and turbine modes, and under steady-state and unsteady conditions. The results indicate that the initial design have a hydraulic efficiency of roughly 90 % in both modes and for a wide range of operating conditions. The unsteady simulations reveal a complex flow pattern downstream the two runners and frequency analysis show that the dominating pressure pulsations originates from the rotor dynamics. Given the promising high efficiency, this initial design makes an ideal platform to continue the work to optimise efficiency and transient operations further.

Axial Flux PMSM Power Take-Off for a Rim-Driven Contra-Rotating Pump-Turbine

“…The PTO consists of two coaxial shafts, which allows the AF-PMSM to be placed on one side of the RPT, housed in a bulb. The RPT efficiency, excluding the hydraulic impact of the PTO, is higher for the shaft-driven RPT, experiencing a maximum of 90% in both pump and turbine mode [28]. As seen in section II the pump efficiency of the rim-driven RPT is only 84%.…”

Evaluation of startup time for a model contra-rotating pump-turbine in pump-mode

“…One of the technologies explored in the ALPHEUS project is a novel shaft driven (SD) contra-rotating pump-turbine (CRPT) design, which is also the subject of this present study. In the ALPHEUS project, an initial design of a SD-CRPT has earlier been 1079 (2022) 012034 IOP Publishing doi:10.1088/1755-1315/1079/1/012034 2 numerically analysed by Fahlbeck et al [6] at both steady-state and unsteady-state conditions. The SD in SD-CRPT is dropped for brevity hereafter.…”