Linear Stochastic Estimation of the Velocity Field from a High-Bypass Nozzle with and without Mixing Devices

抄録

Linear Stochastic estimation (LSE) is employed to compare the large-scale structure of a jet exhausted through a coaxial nozzle configuration with and without mixing devices on the coaxial stream. Particle Image Velocimetry (PIV) is used to measure the streamwise and radial velocity components on a 2D streamwise plane over the first 11 equivalent jet diameters. A comparison of the turbulent kinetic energy (TKE) for these two cases show that the streamwise vortices generated by the mixing devices result in high turbulence levels near the nozzle and reduced turbulence levels downstream. Reconstruction of the TKE profiles using LSE also captured these trends. An in-depth-analysis into number and placement of sensors was performed by correlating the raw data set to the data set formed by reconstructing the field using LSE. LSE was most successful when the reference signals were at the peak amplitude of the TKE radial profiles, and the correlation levels increased as the number of sensors was increased. It was shown that a jet with mixing devices lowered the correlation levels at the downstream positions by breaking up the large-scale structures.