Acoustic characterization of two parallel supersonic jets

In the context of the development of the Ariane 6 launch vehicle, the acoustic characteristics of two parallel, supersonic, heated jets (Mach=3, T=1600K) have been investigated. Acoustic measurements were made by means of four polar arrays of microphones in the far-field, as well as by a circular antenna surrounding the mock-up body, to investigate the upstream sound emission. A simplified configuration, where one of the two jets were obstructed, has also been studied for comparison, in order to analyse the jets interaction e ects. A series of PIV measurements has been conducted with the aim of understanding the mean flow modification induced by the double configuration. Results show no considerable interaction between the hydrodynamic fields of the parallel jets, while a significant change occurs in the sound field. An asymmetric behaviour is observed, depending on the azimuthal observation angle: in the plane containing the axes of the two jets, the increase in the measured sound intensity (wrt the simple jet configuration) is half of the one observed in the perpendicular plane, indicating an acoustic shielding mechanism between the jets.