Mapping Azimuthal Distribution of Supersonic Twin Rectangular Jet Noise

Intense and harmful nature of supersonic jet noise requires comprehensive understanding of its underlying mechanisms, directivity and the development of effective mitigation strategies. Due to their geometric asymmetry, twin rectangular jets are known to radiate noise with varying intensities depending on the azimuthal orientation. While prior research on twin rectangular supersonic jets has predominantly focused on acoustic measurements along two orthogonal planes, such limited perspectives are insufficient to fully characterize the azimuthal characteristics of the radiated sound field. The present study addresses this gap by conducting a detailed investigation of the acoustic signature of twin rectangular jets across a wide range of azimuthal angles, thereby enabling the construction of a three-dimensional noise distribution in the far-field regions. Experiments are conducted in a fully anechoic chamber, with microphone arrays positioned at 150 intervals around the jet axis to capture the variation in acoustic emissions along different measurement planes around the jet. The acquired data are used to reconstruct a three-dimensional hemispherical acoustic map surrounding the nozzle exit. Tests were conducted at various overexpanded, design and under expanded conditions. Acoustic results revealed that the twin jet configuration exhibited highly directional noise radiation, with higher noise intensity along the twin jet planes.