Comparison of the structure of computed and measured particle-laden jets for a wide range of Stokes numbers

摘要

Turbulent particle-laden jets have been the subject of interest for many years on account of their relevance to several practical devices like engines, combustors and gasifiers. While prior experimental studies have examined particle-laden flows at high Stokes number, experimental data on particle-laden jets with particle Stokes number of the order of one and lower have not been available until recently. This study presents results from computations of particle-laden jets for Stokes number ranging from 0.3 to 500 and their comparison with measured results. The mean gas-phase velocity is found by solving RANS equations with a k-ε model for turbulence. The particles are solved in a Lagrangian framework with the coupling between the carrier and dispersed phase modeled using a drag coefficient with a high-Reynolds number correction. Particle-turbulence interactions are modeled using a random-walk dispersion model. The influence of Stokes number on the spreading rate of the carrier and dispersed phase is examined. It is shown that for the range of Stokes numbers considered, the computed results agree with measured particle centerline velocities within about 20%. The changes in particle velocities predicted as Stokes number varies are consistent with measured changes in these variables. While no specific trends can be identified in the differences between computed and measured results that would relate the differences to Stokes number, several parametric studies are carried out to investigate the effect of jet inlet gas phase turbulence intensity, fluctuating particle velocity at the jet inlet, turbulence modulation and the dispersion model employed on jet spreading and centerline velocities.