WHIRL-FLUTTER SUPPRESSION IN ADVANCED TURBOPROPS AND PROPFANS BY ACTIVE CONTROL TECHNIQUES

The feasibility of using the active control technique to suppress the whirl-flutter instability of advanced turboprops is investigated. Aero dynamic vanes are incorporated at the engine nacelle to generate contr ol airloads. The actuator system is driven by a control law that is ba sed on the Kalman filter estimation of the critical aeroelastic modes of the structure. The results demonstrate that the compensator provide s enough controllability to prevent the whirl-flutter onset well beyon d the design speed. The present study suggests that a very efficient v ibration isolation in advanced turboprops may be achieved both by opti mizing the engine-propeller suspension in the actual flying envelope a nd by employing the active control technique to deal with the safe mar gins required by the present aircraft certification regulations.