The oil-film interferometric skin friction techniqie is described and applied to an isolated full-scale XV-15 rotor in hover. This is the first time that this technique has been applied to a rotary wing. The chordwise component of skin friction is presented for both low and high thrust cases. The technique is shown to be capable of revealing the presence of natural transition, leading edge laminar separation followed by turbulent reattachment, and the presence of reversed flow. An extensive region of laminar flow is shown to exist at 3 degrees collective. Transition is shown to move close to the blade leading edge at 10 degrees collective. The high-thrust case, corresponding to 1-g hover, is surprising in that reverse flow is shown to exist over a significant fraction of the chord at the 28 % radial station.
Skin friction measurements on a hovering full-scale tilt rotor
Reibungsmessungen an der Außenhaut eines vollmaßstäblichen Schwenkrotors unter Schwebeflugbedingungen
Journal of the American Helicopter Society ; 44 , 4 ; 312-319
1999
8 Seiten, 9 Bilder, 1 Tabelle, 14 Quellen
Article (Journal)
English
Skin Friction Measurements on a Hovering Full-Scale Tilt Rotor
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