This paper describes the initial experimental results of aeroelastic instability of BF-1 rotors on a transonic axial compressor facility at BIAA. Designing of BF-1 rotors depends upon the principle that the total damping is equal to zero at the point near the stall flutter boundary. The experimental results show that the design principle of BF-1 rotors is correct. Two rotors

BF-1-1 and BF-l-2

have been run from 8000 rpm to 16500 rpm. Several flow-induced vibration phenomena such as stalling flutter

wake-induced vibration

stall vibration of the blades

have been observed in experiments. In addition

a loud monotonous screaming has been heard during the stalling flutter onset. A primary theoretical analysis of this special sound is discussed. This paper also presents the experimental results of effects of the blade tip clearance and the airfoil shape on the stall flutter boundary. By comparison of the empirical methods to predict the stall flutter onset with the experimental results

it is believed that these prediction methods are acceptable.