Linear Stochastic Estimation of a Swirling Jet

Linear stochastic estimation (LSE) was applied to study the coherent structures of a highly swirling jet The swirling jet was produced by a triple annular swirler (TAS) featuring three concentric swirling flows that merge into a turbulent swirling jet. The LSE used statistical theory to provide an estimate of the instantaneous flowfield by reproducing, in space and time, the large-scale coherent structures of the flow using minimum experimental information. LSE turned out to be very efficient for extracting coherent structures from the turbulent flowfield and for describing their dynamics. Although the LSE is highly dependent on the levels of correlation, it enabled the reconstruction of the complete coherent flowfields from the knowledge of only few near-field acoustic signals, providing an effective tool for data reduction to formulate turbulent inflow boundary conditions for large-eddy simulation.