Abstract
•Effect of density variations in non-reacting turbulent round jets is investigated.•Near-field velocity and concentration of Helium, Air and CO2 jets are analyzed.•Centerline velocity and mass fraction decay are affected by initial density ratios.•Lighter gas tends to mix more rapidly with the ambient flow than heavier gas.
Non-reacting turbulent round jets with density variations are computationally investigated in the near field region. Helium, Air and Carbone dioxide are the considered gases emitted from the nozzle exit and discharged in a weakly co-flow air stream, leading to three different density ratios; 0.14 [Helium/Air], 1.0 [Air/Air] and 1.52 [CO2/Air]. Two closure turbulence models are tested; the first order standard k-ε model and the second order Reynolds Stress Model (RSM) and confronted to experimental data. Predicted results elaborated by the RSM model are found to be in good agreement with experiments. Mean and turbulent flow properties, obtained for the velocity and scalar concentration field, are presented for the three simulated jets. It is found that the lighter gas (Helium) tends to mix more rapidly with the co-flow ambient air than heavier gases (Air and CO2). The entropy generation growth is shown to be greater for the Helium jet.