Experimental demonstration of active flow control to reduce unsteady stator-rotor interaction

An experimental investigation is conducted to reduce the unsteady stator-ro tor interaction in a turbofan simulator using active flow control. The fan rotor of a 1/14-scale turbofan propulsion simulator is subjected to circumf erentially periodic inlet how distortions, generated by four stators that s upport a centerbody in the inlet mounted onto the simulator. These wakes ar e reenergized by injecting air from the trailing edge of each stator throug h discrete blowing holes. The flow rate through each blowing hole is contro lled by an individual microelectro-mechanical system based microvalve, The microvalve actuation signal voltage is generated by a proportional-integral -derivative controller and is a function of the wake velocity defect. To de termine the successful reenergizing of the wakes, far-held sound pressure l evel at the blade passing frequency without and with blowing is measured in an anechoic chamber. The active control experiments are performed for two simulator speeds of 29,500 and 40,000 rpm. In addition, the feasibility and advantage of active control is demonstrated by the ability of the system t o respond to changes in the inlet flow velocity.