On the near Field Pressure of a Transonic Axisymmetric Jet

The near field fluctuating pressure of a cold subsonic jet (Mach 0.85) issuing from a contoured convergent nozzle was studied. Conventional time series analysis (i.e., correlation and spectral analysis) as well as a wavelet analysis were used to characterize time-dependent events thereby revealing features consistent with current understandings of jet noise while also uncovering modal features consistent with previous measurements of the jet flow field itself. Specifically, the measurements reveal extensive sources of multiple frequencies in the streamwise direction. The near field information of the present investigation should help to bridge our understanding of the relationship between the velocity field and the far field acoustic emission associated with subsonic jet noise as well as supply a data set that can be used for verification of computational efforts.

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