Flow Visualization of the Propeller with Small Blades on the Blade Tips

摘要

A new type propeller derived from "winglets" was investigated. This propeller, of which efficiency increases from 1 to 4% on the working point, was also fitted small blades at the blade tips likely to "winglets" , so the authors named it "bladelets". These are for the purpose of reducing induced drag from tip vortices, and this propeller has the second aim to reduce pressure fluctuation and cavitation noise. This paper presents the results of many flow visualization method on these bladelet propellers, such as dye injection method for the tip vortex, oil film method concerning the surface flow of propeller, and tuft grid method for the race. Those results were suggested the reduction about the strength of tip vortex by the small blades, compared with the conventional propeller. The results of the cavitation tests were further shown, and the same results wore confirmed about the strength of the tip vortex.