Investigation of actuator placement approaches for active vibration control in the aircraft engine

To improve the comfort in the fuselage of a business jet by reducing the vibration induced by the unbalance in the engine, the active damping method was studied and compared with the passive system with squeeze film dampers at bearings. In the active control method, the positions of actuators play an important role in the effectiveness of vibration reduction. Two approaches of actuator placement along the vibration transmission path, i.e. at the bearing and at the mount system, were investigated in the following steps: (1) robustness of the active system, (2) optimal effectiveness and (3) realizable effectiveness. It is found that the passive damping should not be completely replaced by the active one, but work in cooperation with it. The optimal effectiveness, in terms of root mean square of acceleration at the junctions between the fuselage and the mount system, shows that the actuation at the vibration source and on the mount system brings reduction with averages of 23.3dB and 7.1dB, respectively. The realizable effectiveness was further investigated with filtered-x least mean square algorithm and evaluated in terms of acceleration and vibrational power. In acceleration, the realized effectiveness is comparable to the optimal effectiveness and it is shown that with this control algorithm over 70% of the optimal effectiveness can be reached either in the front or in the rear, depending on the actuation approach. The results in power give an overview of the different mechanism of vibration transmission with each actuation approach.