Theoretical Modelling Of Broadband Shock Associated Noise in Asymmetric Jets

Supersonic jets operating at off-design conditions produce Broadband Shock Associated Noise (BBSAN) which is characterized by multiple peaks in the jet broadband noise in the farfield. A physical acoustic analogy model devoid of limitations of scaling-law models and based purely on flow-field data obtained from a RANS model is validated for two axisymmetric cases. The present work focuses on extending this model to jets of varying eccentricity. The effects of jet asymmetry on the formation of shock-cells and their subsequent interaction with turbulent eddies which determines BBSAN has been investigated. The elliptical nozzles seem to be acoustically more beneficial with regards to BBSAN in comparison with the axisymmetric nozzles, while maintaining similar operating conditions as the axisymmetric cases, with minimum changes to the nozzle geometry.