DAMPING PREDICTION FOR A STALLED ROTOR IN FLAP-LAG WITH EXPERIMENTAL CORRELATION

A direct numerical time-marching integration is used to compute the tr ansient response (free oscillation) of the flap-lag motion of a rotor. A time-domain quasilinear model identification technique is applied t o identify the damping and frequency for the regressing mode, except f or the chaotic lag response when stall occurs. Numerical examples and correlation with previous experimental results are provided. It is fou nd that the present theoretical method has improved the flap-lag stabi lity analysis with respect to agreement with experiment.