Identification of broadband acoustical sources in the cylindric duct using a hybrid reconstruction method

Abstract

Beamforming and inverse methods are widely applied to the localization and reconstruction of acoustical sources inside ducts. Identification of in-duct sources using the conventional beamforming method would lead to poor spatial resolution and even fail at some specific frequencies with multiple virtual sources. Employing the inverse method would improve the accuracy of inner duct source localization, however, severe deviation of source intensity results calculated by the inverse method from actual results would occur due to tremendous dimensions of inversion and regulation process of the transfer function matrix. To reduce the dimensions of inversion and further improve the accuracy of source identification, a combined imaging methodology is proposed. The beamforming method is firstly applied to locate regions containing sound sources preliminarily, then an inverse method is applied to regions contributed by beamforming to remove ghosts and side lobes. Numerical simulations are implemented to validate the method. Azimuthal and radial localization results indicate that the combined imaging method is with better spatial resolution than beamforming or inverse methods. Reconstructed results of the source's volumetric velocity demonstrate that the proposed method has a lower deviation of source intensity than the inverse method.