Reduction of noise on large size pipes by inserting acoustic grilles

This paper deals with the problem of silencing relatively large intake pipes by inserting reactive and dissipative absorption sections inside the end of the pipe with a cascade arrangement to form an acoustic grille.Experiments have been carried out on various internal configurations of the same type of section for silencing intake pipes.This paper describes the application of an acoustic grille for silencing the intake end of an engine cooling pipe on a FIAT IVECO'bus. Experimental results have shown a noise attenuation of about 5 dB(A) on that specific source.