Acoustic imaging of sources located either external, internal or on the surface of an arbitrary body.

摘要

In the present study, a new non-contact remote method is developed to reconstruct the location and amplitude of a harmonic source distribution in a fluid based on the associated acoustic pressure field on a measurement surface which is in contact with the fluid. An inverse or backward projection method based on the Singular Value Decomposition (SVD) method is utilized to reconstruct the source distribution that created the acoustic pressure field. Point source distributions located above an axisymmetric rigid plane and line source distributions located outside infinite rigid circular and elliptical cylinders are investigated. Numerical results show that the backward projection method is able to locate and to determine the strength of harmonic near-field sources in the external fluid which are separated by less than 0.01 of a wavelength.; The reconstruction of the harmonic normal velocity and pressure surface distributions on a three-dimensional body based on the associated acoustic pressure field on a measurement surface located outside the body is addressed next. Prescribed normal velocity distributions on a spherical shell are investigated as special cases of interest. The case of different ratios of length to radius cylindrical shells with hemispherical end caps is also investigated. Numerical results for the reconstruction of normal velocity and pressure fields on the surface of the body show excellent agreement with the prescribed normal velocity and pressure fields over a wide normalized frequency range.; Finally, the backward projection of the acoustic pressure field on the internal surface of a body to determine the internal harmonic source distributions which generated the field is considered. Axisymmetric source distributions in an infinite rigid circular cylinder duct are investigated. Monopole sources, dipole sources, and quadrupole sources are addressed. Numerical results show that the backward projection method is able to locate and to determine the strength of harmonic source distribution which are separated by less than 0.004 of a wavelength.