Development of a propeller-type hollow micro-hydraulic turbine with excellent performance in passing foreign matter

摘要

This study develops a micro-hydraulic turbine with excellent performance in the passage of foreign matter included in the water flow. The runner has four blades, with a circular hollow around the rotating axis to pass foreign matter through the runner. The ratio of the hollow diameter D-2 to the runner outer diameter D-1, D-2 /D-1, is defined as the hollow ratio epsilon. Laboratory experiments are conducted by introducing polyester fibers into the water flow as foreign matter. The turbine efficiency eta decreases with increasing epsilon under the fiber-free condition. For the runner having no hollow (epsilon = 0), eta decreases drastically with increasing the mass of the introduced fibers. This is due to the blockage of the runner by the fibers. But eta for the runners provided with the hollow decreases less. This demonstrates that the hollow makes the fibers pass successfully through the runner. Additional experiments are conducted using the runner with epsilon = 0.25. The blade leading edges near the central axis are rounded with radius R. When R/D-1 = 0.1875, the decrease in eta due to the fibers is extremely small. The rounded leading edges successfully prevent the runner from catching the fibers, demonstrating that they effectively heighten the passage performance of foreign matter through the runner. (C) 2018 Elsevier Ltd. All rights reserved.