Study on Blade Property Measurement and Its Influence on Air/Structural Loads

In this study, the structural properties of Second Higher-Harmonic Aeroacoustic Rotor Test blades are determined using state-of-the-art test techniques. The measurement includes bending and torsion stiffnesses, section geometric offsets, and mass and inertia properties. Several Second Higher-Harmonic Aeroacoustic Rotor Test blades, including the original instrumented blade used for the wind-tunnel test campaign in 2001, as stated by Yu etal. (The HART-II Test: Rotor Wakes and Aeroacoustics with Higher-Harmonic Pitch Control (HHC) InputsThe Joint German/French/Dutch/US Project, Proceedings of the 58th American Helicopter Society (AHS) Annual Forum, American Helicopter Soc., Montreal, June2002) are used for the activity. A finite element-based cross-section analysis combined with an x-ray computer tomography technique is employed for the cases where no mechanical measurement is available or attempted. The resulting structural properties are correlated against the earlier estimated values, which have extensively been used in the literature for the validation of the Second Higher-Harmonic Aeroacoustic Rotor Test rotor. A substantial deviation is observed between the present measurement and the earlier property result. The comprehensive rotor dynamics analysis is performed to quantify the impact of the measured blade properties on the aeromechanics behavior of the rotor. The location of the center of gravity is demonstrated to be the most influential factor affecting the deviation and the sensitivity of the aeroelastic response of the rotor.