SPATIAL VELOCITY CORRELATIONS AND NEAR FIELD PRESSURE MEASUREMENTS FROM A HEATED TRANSONIC AXISYMMETRIC JET

摘要

Turbulence properties and the near field pressure of a Mach 0.85 jet at two different static temperature ratios (0.87 and 2.4) are studied. The turbulence properties were studied using PIV measurements which were performed with the light sheet aligned in the radial and the streamwise directions at locations between 3.3 and 8.2 jet diameters downstream from the nozzle exit. Measurements of the near field pressure fluctuations were acquired using a linear array of 6 pressure transducers evenly spaced from 3.45 to 8.45 jet exit diameters. From the PTV measurements it was observed that the heated jet is narrower than the unheated jet and has a higher peak normalized TKE. The highly correlated area of the 2 point spatial velocity correlations is larger for the unheated jet than the heated jet. The measurements from the pressure transducers reveals that the relative amplitude of the mean fluctuating pressure is slightly higher for the heated jet after the end of the potential core. The convection speed of the waves propagating along the pressure sensor array was calculated to be larger for the heated jet.