Inverse aeroacoustic problem for a rectangular wing

An investigation is made of the feasibility of aeroacoustic inversion, wher e the pressure on a thin, flat, rigid rectangular wing undergoing rigid osc illations or interacting with unsteady, subsonic flow is to be predicted fr om the far-field acoustic signal. This problem is ill-posed because small p ressure fluctuations in the far field are larger in the near field by a fac tor equal to the reciprocal of the distance from the wing. In the inverse m odel, this ill-posedness manifests itself in the kernel of a two-dimensiona l Fredholm integral equation of the first kind. Discretization of this inte gral equation using a physically meaningful collocation series results in a n ill-conditioned system of equations which is solved using the singular va lue decomposition (SVD). The SVD generally requires regularization techniqu es to discard redundant or unphysical information. An algorithm is develope d for optimally determining the near-field pressure without relying on a us er-specified regularization parameter. Tests using numerically generated in put data show the inversion is feasible and accurate for accurate input dat a, The inversion remains feasible when errors are introduced in the far-fie ld measurements and the measurable parameters of the flow.