Study on the effects of runner geometric parameters on the performance of micro Francis turbines used in water supply system of high-rise buildings

With the increasing emphasis on clean energy, there is growing attention to the use of microturbines or pumps as turbines (PATs) to recover excess hydraulic energy in the water supply system (WSS) of high-rise buildings. In this paper, a micro Francis turbine for WSS in high-rise buildings was presented, and the effects of runner geometric parameters on turbine performance were investigated through computa-tional fluid dynamics (CFD) and lab tests. In the research process, based on the theoretical design results and the numerical optimization of blade exit angle and blade shape, a turbine model was obtained for laboratory testing. The test results show that the Francis turbine has a relatively good performance in both energy generation and water head reduction. In addition, the feasibility of the used runner design method was verified in this special working condition by comparing the experimental performance of turbines with different runner inlet widths. Based on a numerical model that has been validated by experimental results, further optimization for blade thickness and blade number was carried out through CFD simulations. The simulation results show that blade thickness and blade number can affect energy consumption and pressure distribution in the runner and thus affect turbine performance, and there are optimal values to achieve optimal turbine performance. And the optimized model had an output power of 148 W and an efficiency of 21.23% at the design condition.(c) 2022 Elsevier Ltd. All rights reserved.