The performance of a rotor with slotted tip blade tips was examined on a whirl stand. The rotors were tested in 2-bladed and 4-bladed configurations. Flow visualization was conducted to examine the effects of slot location and the number of slots in the effectiveness of diffusing the concentrated vorticity at the vortex core. The following conclusions have been drawn from the study: 1. The power increases of the slotted blades were measured to be less than 5 % for the 2-bladed rotor system and 10 % for 4-bladed rotor of the baseline blade cases, respectively. This corresponded to a maximum loss of figure of merit of only about 4 %, and as low as 2 % at higher values of blade loading coefficient. The results suggest that the slotted tip blade will be applicable for use on other types of rotors with only a minor performance penalty. 2. It was observed from flow visualization that the three slots were enough to defuse the tip vortex, although perhaps not quite as much as using four slots. Fewer slots were shown to have a lower performance penalty. However, there was some evidence of the reformation of the tip vortex at older wake ages when using three or fewer slots. For this reason the choice of four slots is considered to be the most useful in terms of diffusing the tip vortex until further work in optimizing the slot design can be undertaken. 3. Further work is still required to examine the underly ing fluid dynamic processes associated with the slot ted tip. It would appear that detailed flow measurements at the slot exits and in the immediate tip vortex roll up region are key to achieving this understanding.


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    Title :

    Hovering performance of a rotor with slotted blade tips


    Additional title:

    Schwebeleistung eines Rotors mit gefächerten Blattspitzen


    Contributors:

    Published in:

    Publication date :

    2004


    Size :

    10 Seiten, 21 Bilder, 4 Tabellen, 20 Quellen


    Type of media :

    Conference paper


    Type of material :

    Print


    Language :

    English






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