Mach-number dependence of acoustic source properties in high speed jets Part II: Event-based description

For jet noise at three Mach numbers, we isolate and document properties of acoustic events. Pattern recognition in the time-frequency domain isolates events common to farfield acoustic data and near-field signals obtained from time-resolved PIV. From the signals treated in Part I, we identify the excerpts that contribute most to the cross-correlations. The time-frequency decomposition is achieved with continuous wavelet transforms. We identify far-field events (MM) responsible for the cross-correlation between microphones, and DM events that account for the cross-correlation between the kinematic diagnostics and one microphone. MM and DM events are intermittent in time and frequency. The lists of MM and DM events, including time of occurrence, frequency and magnitude, are compared for nine sets of data featuring three different Mach numbers and different window locations. We match the events individually (near-and far-field excerpts) and document some of their collective properties.