An Investigation of the Isothermal Confined Double Concentric Jet System

Abstract

—The Craya–Curtet number for the isothermal confined double concentric jet system has been derived. Velocity, turbulent shear stress and intensity of turbulence profiles have been measured for different operating conditions, corresponding to different values of Craya–Curtet number. Essential flow features of the system such as radial profiles of mean axial velocity and recirculation have been found to be correlated with the Craya–Curtet number. The turbulent shear stress profiles have been found to depend on position in the flow field, and the Reynolds numbers of the primary and secondary streams. The intensity of radial turbulence has been found to be approximately half the value of the intensity of axial turbulence. Experimentally measured velocity profiles have been compared with those predicted by solving the equations of motion by the finite difference technique. Two types of effective viscosity values have been used in these calculations, one based on a simple turbulence model and the other based on experimentally measured turbulent shear stress profiles. It has been found that the use of the second type of effective viscosity values slightly improve the agreement between measured and predicted values.