AN EXPERIMENTAL AND NUMERICAL INVESTIGATION OF TURBULENT MIXING OF SUBSONIC GAS JETS IN A COAXIAL CONFIGURATION

摘要

Measurements of mean temperature, velocity, the normal stresses and Reynolds shear stress are reported in the mixing region of coaxial jet flows. The measurements were obtained with three different outer jet exit temperature of 15, 30 and 45℃ above ambient with the constant exit Reynolds number. The satisfactory representation of the jet is dependent on adequate representation of turbulence in the jet, which determines its spread and mixing. The standard k-ε model is used to predict the mean and turbulent flow fields. The deviation of predicted results from experimental kinetic energy at high exit temperature difference can be due to the anistotropic charter of the mixing region. Measurements performed at different axial stations provide a broad database against which result of calculation procedures embodying k-ε turbulence model can be compared. The normal stress results show substantial deviations from isotropy. This clearly indicates the need to consider the normal stresses in any turbulence model of such flows.