Experimental investigations of rotor-fuselage aerodynamic interactions using a helicopter powered model

This paper presents wind tunnel experiments of helicopter rotor-fuselage interactions. Several test campaigns have been conducted in the ONERA F1 subsonic wind tunnel on a Dauphin 365N model equipped with a powered main rotor. Numerous measurements have been performed during these tests: time-averaged and time-dependent fuselage pressure measurements, 6-components balance measurements, and Particle Image Velocimetry (PIV) measurements. This last technique allows to measure instantaneous velocity field in large planes around the helicopter for several blade positions along the rotor revolution. 2-components (2C) PIV results and 3-components (3C) stereoscopic PIV results are presented. Each measurement technique accuracy and repeatability are first discussed, thanks to the large number of test points performed. The influence of the rotor downwash on the fuselage and the location of its impingement are then presented by analyzing the test points for different advance ratios and rotor thrust coefficients. The PIV results give finally a detailed description of the rotor wake in presence of the helicopter fuselage.

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