Wind Tunnel Modeling of High Order Rotor Vibration

Measured and predicted high order (8/rev) vibratory hub loads are presented for a Mach-scaled ten foot diameter four-bladed rotor. Test hub loads obtained from three dynamically calibrated balances and from performing generalized coordinate analyses using measured blade response are presented. Results show good agreement for the ability to measure fixed system 8/rev vertical and moment hub loads. Analytical predictions using the Tech-01 computer program are in very good agreement with test results for 8/rev vertical hub load magnitudes and are in reasonable agreement for 8/rev hub moment magnitudes.