Scattering of turbulent-jet wavepackets by a swept trailing edge

• DOI: 10.1121/1.4971425
• Publication Date: 2016-12-20T01:30:34Z
• Authors: Selene Piantanida; Vincent Jaunet; Jérôme Huber; William R. Wolf; Peter Jordan; André V. G. Caval...
• Keywords: 0103 physical sciences; 0202 electrical engineering, electronic engineering, information engineering; 02 engineering and technology; 01 natural sciences

Installed jet noise is studied by means of a simplified configuration comprising a flat plate in the vicinity of a round jet. The effects of Mach number, jet-plate radial distance, and trailing-edge sweep angle are explored. Acoustic measurements are performed using a traversable 18-microphone azimuthal array, providing pressure data at 360 points on a cylindrical surface surrounding the jet-plate system. Key observations include a decrease, with increasing Mach number, of the relative level of the scattered field in comparison to the uninstalled jet; an exponential dependence of the scattered sound pressure level on the radial jet-plate separation; and considerable sideline noise reductions with increasing sweep angle, with which there is an overall reduction in acoustic efficiency. The measurements are compared with results obtained using a kinematic wavepacket source model, whose radiation is computed in two ways. A TGF for a semi-infinite flat plate is used to provide a low-order approximation of the scattering effect. Use of a more computationally intensive boundary element method provides additional precision. Good agreement between model predictions and experiment, encouraging from the perspective of low-cost prediction strategies, demonstrates that the models comprise the essential sound generation mechanisms.