Abstract
Stochastic Estimation (SE) is utilized to investigate the large-scale structure of a jet exhausted through a baseline axisymmetric nozzle and two chevron nozzles with different penetrations. Particle image velocimetry (PIV) was used to measure the streamwise and radial velocity components on a 2D streamwise plane over the first 15 jet equivalent diameters. Two 16 microphone, linear, near-field arrays separated by 180° in the azimuthal plane were simultaneously acquired with the PIV measurements. The analysis included investigation of the near-field pressure spectra and flow field mean velocity and Turbulent Kinetic Energy. SE was used to reconstruct the velocity field from the acquired pressure data. The optimal number and optimal placement of sensors was investigated to obtain the best reconstructed velocity. Near the nozzle, the optimal sensor location was near the jet while further downstream, SE was better when the microphones were slightly farther away. This is directly related to the wavelength of the large-scale structures which increased downstream. SE was successful at reconstructing the TKE profiles in shape but significantly under predicted the amplitudes. It was also shown that SE was not as successful reconstructing flow exiting the chevron nozzles due to a drop in correlation between the flow velocity and near-field pressure. Even with the lower correlations, the shape of the TKE profiles were successfully reconstructed using SE for the chevron flow fields.
Published Version
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