<p>With the recent rise in the importance of environmental issues, efforts to reduce carbon dioxide emissions have been made worldwide. As part of this effect, research on renewable energy is being actively conducted to reduce the use of fossil energy. Hydropower is one kind of renewable energy source, and it never produces carbon dioxide because it generates power using a turbine with water as the working fluid. Micro hydropower has a smaller installation capacity relative to general hydropower, so it has less restriction on space. Particularly, micro hydropower in pipes is highly safe and sustainable, and there is pressure in pipes to transport water, hence it is possible to generate power by harvesting unused pressure energy. Also, most buildings have water pipes and sewer pipes, so there are fewer limitations to introducing micro hydropower in pipes. Many researchers have studied micro hydropower through energy harvesting in pipes and designed various types of turbines. In this study, a mixed flow turbine is introduced to collect unused energy in pipes, and numerical analysis was conducted using ANSYS CFX to estimate the performance. Efficiency was adopted as an indicator to evaluate the performance, and the performance of three different hub shapes, convex, concave, and conical, was investigated. When it comes to numerical analysis of the reaction turbine, it is known that the numerical error is small at the best efficiency point with Reynolds-Average Navier-Stokes turbulence models. Therefore, k-ω Shear Stress Transport was used for turbulence model to simulate the flow separation at the blades, and the best efficiency point was found by changing the rotational speed of the runner. The turbine used in this study was modeled except for the guide vane unlike the general turbine because it is small in size with a pipe diameter of 50 mm. For this reason, it is difficult to determine the velocity component at the leading edge of the blades, so design of experiment, not velocity triangles, was conducted to design the blades of the mixed flow turbine, and NACA 0006 profile is used as a blade model. As a result, three different hub shapes have the best efficiency point between rotational speeds of 3000 rev/min and 3200 rev/min. The convex hub showed the highest efficiency, which was 1.60% and 3.63% higher than the conical and concave hub, respectively. Consequently, the convex hub configuration showed the best performance.</p>

Effect of Hub Configuration on the Performance of Mixed Flow Turbine for Micro Hydropower in Pipes

Paper Proceedings: https://asmedigitalcollection.asme.org/FEDSM/FEDSM2021/volume/85284

ASME 2021 Fluids Engineering Division Summer Meeting (FEDSM2021)

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