Low noise design and testing methods for aeroengine are indispensable for civil aviation industry with the public environmental convern growing and the stringent regulations established. A novel array testing approach is proposed to reconstruct spinning modal fan noise amplitude from scattered sound wave measurements outside the jet flow downstream to an unflanged duct. The proposed approach relies on the forward propagation model based on the Wiener-Hopf method. The key contribution of this work is the development of the inverse acoustic scattering methods using a non-classical beamforming and a compressive sensing strategies. The performance of the proposed strategies are demonstrated with various numerical simulations, which show that the deconvolution method is more generic while the compressive sensing method is more efficient. The reconstruction results from both methods are comparable in terms of accuracy and dynamic range. Overall, the proposed testing approach should be able to extend the current duct acoustic array testing capability and help the design and evaluation of low-noise ducted fan system.

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