Scattering Of Turbulent-jet Wavepackets By A Swept Trailing Edge

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)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 wave-packet 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. (C) 2016 Acoustical Society of America.140643504359EU [FP7-AAT-2012-RTD-1, 314692]AirbusFundacao de Amparo a Pesquisa do Estado de Sao Paulo, FAPESP [2013/03413-4]Science without Borders program [A073/2013]Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP