Intermittency of the near pressure field induced by a compressible coaxial jet

A novel method of analysis based on the combined use of the wavelet transform and linear stochastic estimation (LSE) is applied to pressure and velocity signals obtained in a coaxial jet at low subsonic flow conditions. The aim of the analysis is to identify and clarify the role of intermittency in the generation of noise. The wavelet analysis extracts intermittent events from the near field pressure signals and the LSE technique identifies velocity fluctuations which are linearly associated with the selected pressure fluctuations. A frequency-wavenumber filtering procedure is also applied to the near field pressure in order to separate the hydrodynamic and the acoustic components. The results achieved helps to identify and localize fluid dynamic events responsible for the generation of near field hydrodynamic and acoustic intermittent pressure fluctuations.