Study on Foreign Body Passage in an Ultra-Small Axial Flow Hydraulic Turbine

Abstract

Ultra-small axial flow hydraulic turbines, which are of the size of your palm, are a type of turbine that can be applied to the low heads of existing pipelines and open channels. However, due to their compact size, they are more likely to malfunction in case of foreign body contamination. In our study, we observed the passage of foreign bodies through an ultra-small axial flow hydraulic turbine and their encounter with the blocking mechanism of the turbine. We selected polyethylene ropes of varying lengths with a wire diameter of 5 mm to serve as foreign bodies. By varying the length of the rope, we were able to visually observe the movement of the foreign body. The turbine’s blocking mechanism can be broadly classified as guide vanes or runners. In the case of runner, blocking occurs when foreign bodies are bent and are caught at the leading edge of the blade. The passage rate through the hydraulic turbine is largely dependent on the passage rate at the runner section, which decreases proportionally with the length of the foreign body and the rotational speed of the blades.