Methods and technologies to control the vibrations and noise on profiles excited dynamically by a fluid flow like vanes, rotor blades, or plane wings are tremendously needed. The following manuscript relies on a preliminary research proposing a vibration and noise control system integrated into the lower and upper profile of an outer guide vane prototype, consisting of five flush-mounted piezoelectric cells. To control the piezoelectric transducers, an impedance control circuit has been designed to dissociate current and voltage, and control directly their complex impedance as a frequency-dependent function. Then, the negative capacitance control principle is used to synthesize the controller as it avoids complex identification methods of the structure. Only by determining the optimal negative capacitance, it is possible to control the vibration level and acoustic transmission of the profile on a bandwidth around the main vibration mode of each cell. Hence, an average reduction level of −6dB is achieved on the vibration and acoustic transmission level for a large bandwidth around 3500Hz and 4500Hz, confirming the performance of negative capacitance control with the advantage of not needing the usual complex identification process of the structure model.
In this paper, experimental results of broadband noise reduction in an acoustic flow duct are presented. An active liner composed of an array of electroacoustic absorbers is used. The control law is based on the pressure-based, current driven digital architecture for impedance control with a local control strategy. A wind tunnel test rig named Caïman has been used for the experimental validation. The results confirm the adaptability and the stability of the whole system with the local control strategy. The air flow slightly reduces the efficiency while maintaining the adaptability and the stability.
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