AIRCRAFT INTERIOR NOISE REDUCTION THROUGH A PIEZO TUNABLE VIBRATION ABSORBER SYSTEM

摘要

Turboprop aircrafts, such as Airbus A400M, are challenged amongst others by high interior noise levels due to tonal propeller-induced vibrations of the aircraft structure. One approach for interior noise reduction is the reduction of fuselage vibrations by vibration absorbers. In the case of variable propeller speed, the vibration absorbers have to be tuned to the variation of the blade passage frequency (BPF) and its harmonics. In this paper, a tuneable vibration absorber (TVA) system based on the emerging piezoelectric technology is proposed. Embedding piezoceramic elements into a GFRP leaf-spring represents the core element of a force generator amenable to direct electrical control. Depending on the control law, a tuneable vibration absorber is realized. In general, an actuator for active vibration control is achieved. For the Piezo-TVA system proposed, piezo leaf-spring absorbers have been designed for a fundamental BPF at 87.3Hz as well as its first harmonics. Absorber prototypes are manufactured and control laws are designed, simulated and implemented into a dSPACE system. The system is tested on a realistic aircraft fuselage panel (main dimensions similar to A320) installed into a transmission loss test suite where the panel is acoustically excited. A vibration reduction performance of up to 40dB and a noise reduction performance of up to 13dB are demonstrated. Moreover, a multi-mode operation of the TVA system is presented as well as its high flexibility required for optimum system configuration during flight tests. The proposed system is extremely beneficial with respect to guaranteed performance, high flexibility and a minimum weight realization.