Experimental feasibility of in‐duct sound source reconstruction

Teresa Bravo, Cédric Maury
2008 Journal of the Acoustical Society of America  
Acoustics 08 Paris develop noise reduction techniques at acceptable cost in the aeronautical sector. A sound characterisation of the aero-acoustic sources in the nacelle acoustic duct problem plays a crucial role. In this study, it is first shown how the liners optimized impedances strongly depend on the noise source characteristics under both tonal and broadband excitation conditions, and in the latter case, for varying degree of correlations between the random source strengths. It is found
more » ... ths. It is found under which conditions source identification methods, such as pointwise modelbased inverse techniques, are able to provide reliable models of equivalent sound sources from a limited number of in-duct measurements, but which require a priori knowledge of the source location. The performance of such methods are compared with two different approaches, namely the use of focussed in-duct beamforming techniques to locate the unknown sources, and a decomposition of the assumed source strength into angular Fourier series for both the location and the determination of the source amplitudes. Experimental results are presented for the location and the reconstruction of the particle velocity spectrum of wall-mounted compression drivers from in-duct measurements.
doi:10.1121/1.2933758 fatcat:cbqq7dwbhzeovb34f2qsy6lfn4