Measurements of mean velocity and turbulent intensities in a free isothermal swirling jet

Abstract

The objectives of the present measurements are to provide data against which results of numerical prediction procedures can be compared, and quantitative information on the behavior of all turbulent stresses and their correlation to spatial distribution of mean velocity gradients, with a view to improving current understanding of relevant transport processes and to guiding turbulence modeling and prediction efforts of such flows. A laser velocimeter, operating in a constant time interval sampling mode, was used to obtain the measurements. Measured values are presented for the case of strong swirling velocities (with recirculating region). The location and extent of the recirculation region is established. Contours of turbulent kinetic energy, derived from measured data, locate the high-turbulence intensity zones (i.e., zones of intense mixing). Experimental data indicate a strong dependence of the turbulent stresses on the local strain of the mean flow in most regions of the flow, which suggests that an eddy viscosity type of turbulence model, e.g., the k-epsilon model, rather than a Reynolds stress model could be acceptable for the prediction of such flows. 22 references.