Computational and experimental study of an ultra-low head turbine

Abstract

As the threat of limited energy has reached its peak, a system that utilizes majority of the unutilized sites to extract energy is demanded. The project work, presented here, aims to propose an efficient system to exploit the low head sites, test and verify the technical feasibility and economical affordability of thus proposed system. The research was carried out to develop ultra-low head turbines that exploits the sites with lower head and lower discharge using only limited hydraulic and mechanical components satisfying the economic viability [1]. Three models were prepared and one was successfully tested to verify the operating principle called "Static Pressure Difference principle". Focusing on blade profile, mesh generation CFX package was used to analyze the fluid flow through turbine hub and blade. This approach was carried out on three different turbine models with straight, twisted and curved blade profiles and results were used for efficiency evaluation of each turbines. The simulation result showed curved profile to be best efficient profile than other two with 87.03 % efficiency and well distinguished pressure and suction side within a blade. The produced power was 3 W at rotational speed 12 rpm anticlockwise with torque of 2.45 N-m at the flow rate of 6 l/s. The computational analysis was ensued by scaled model testing in a small irrigation canal with a channel system. The testing showed curved blade turbine model's efficiency of 64.36 % with output power of 2 W at rotational speed of 15 rpm anticlockwise with torque of 1.28 N-m at the flow rate of 6.4 l/s. The head difference was maintained at 5 cm for both type of analysis.