The use of an array of Herschel-Quincke tubes to improve the efficiency of lined ducts
Résumé
The scattering matrix results of Herschel Quincke (HQ) components waveguide resonators installed in combination with an acoustic liner (HQ-liners) are presented in this paper. This approach aims at controlling both tonal and broadband noise to improve the liner efficiency. It consists in installing circumferential arrays of Herschel-Quincke tubes on a main duct in a serial association with a locally reacting liner of known impedance. Results for the scattering matrix of this system are deduced from an analytical model and compared with experimental and numerical data showing a good agreement. Analysis of the scattering matrix coefficients points out the modal conversion properties dependence upon the number of HQ tubes along the circumference. Results of the transmission loss shows that to choose an optimal HQ configuration with respect to the liner properties leads to an important improvement of liner efficiency.