Exploitation of the hydropower potential downstream of a weir

Hydraulic machines are currently becoming of interest to enhance the small-scale hydropower potential and perform energy recovery as well. One of the most interesting applications is the use of simple and low-cost turbines in mountain weirs that have not been fully exploited yet. A critical issue in these applications is the risk of strong atmospheric events and flood with high solid transport that could lead to possible damages. This paper presents a fluid dynamic analysis of an axial propeller prototype made of plastic material and designed by a company located in South-Tyrol (Italy) to be installed in weirs. The idea is to propose a compact geometry with low-cost materials that can be easily replaced in case of failures. The performance of the hydraulic turbine was investigated and two geometry modifications upstream the stator vanes have been proposed to improve their performance. Results showed that the Best Efficiency Point (BEP) conditions in terms of flow rate and head did not change. The efficiency increased up to 0.54, namely by +2% with respect to the initial geometry thanks to the reduction of flow instabilities at the entrance of the stator vanes that are the main causes of the efficiency losses in turbomachinery.