Simplified and Precise Design of Crossflow Turbine Power Transmission Components

Abstract

Despite the merits of small hydropower (SHP), coupled with the perennial inadequate and unreliable electricity supply in SSA, the huge SHP potential in the region is hugely untapped. This is largely attributed to the lack of adequate technical components for the development of SHP turbines, which are: technical personnel, and production facilities in the region. The hydraulic power possessed by flowing water in SHP resources can be harnessed and transformed into usable electrical energy via the deployment of a hydro turbine plant. Commonly used hydro turbines include crossflow (CFT), Pelton, Turgo, and Francis turbines. Amongst these turbines, CFT is mostly applied in low head sites and has efficiency ranging from 70–85%. The CFT power transmission subsystem is considered vital to its performance; the shaft, which transmits the generated motion to drive the alternator, is the most critical part of the CFT transmission subsystem and it requires careful design and production processes. This study centres on the development of a simplified systematic design process for power transmission shaft, pulley, and belt, to facilitate CFT power generation efficiency. .Further, the study is geared towards boosting CFT technology capacity domestically for the benefit of local production. The hydrological properties of the Ayiba SHP site in Osun state, Nigeria, were adopted for this work as a case study. The head and power for this resource are 11.8 m and 122.4 kW, respectively, and are served as the fundamental parameters for the design of the power transmission subsystem. The design computation shows that a shaft of diameter 65 mm and a D-type of V-belt with a corresponding pulley will be required to transmit the generated turbine power to the alternator. A 3-D model was created based on the design values and this was used to validate the integrity of the shaft by static stimulation. The simulation result, which is based on von Mises was satisfactory as the highest stress obtained in the shaft was 205 N/mm2; resulting in a 2.6 factor of safety.