In this paper, we theoretically, numerically and experimentally demonstrate the acoustic isolator effect in a 1D waveguide with direction dependent controlled boundary conditions. A theoretical model is used to explain the principle of non reciprocal propagation in boundary controlled waveguides. Numerical simulations are carried out on a reduced model to show the non-reciprocity as well as the passivity of the system, through the computation of the scattering matrix and the power delivered by the system. Finally, an experimental implementation validate the potential of programmable boundary conditions for non reciprocal propagation.
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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