A STUDY ON THE TURBULENT MIXING OF A CO-AXIAL ROUND JET CONSIDERING THE VARIATION OF THE EDDY REYNOLDS NUMBER

Abstract

The turbulent mixing of a co-axial jet is studied theoretically and experimentally. The analysis is similar to that which one of the authors has ever performed for a plane jet. Namely, the variation of the mixing characteristics towards downstream from the nozzle exit is discussed from the viewpoint that the proportionality factor of Prandtl's hypothesis is equal to the reciprocal of the eddy Reynolds number based on Townsend's large-eddy hypothesis. It is found that the variation of the proportionalty factor depends not only on the excess-velocity ratio as in the case of the plane jet but also on the excess-velocity ratio at the nozzle exit. A good agreement is obtained between theory and experiment.