2-WAY COUPLING AND MODULATION EFFECTS IN PARTICLE-LADEN TURBULENT ROUND JETS

If the momentum flow rate of particulate phase at the nozzle exit is greater than about one tenth of that of gaseous phase, the gas phase properties can be modified by the presence of the particles. This phenomenon, known as two-way coupling, is theoretically investigated by a stochastic separated flow model. This model employs the particle-source-in-cell approach, which involves dividing the spray into representative samples of discrete drops whose motion and transport are tracked through the flow field, using Lagrangian formulation. An Eulerian formulation is employed to solve the governing equations of the gas phase using a k-epsilon turbulence model. The effect of particles on the gas phase is considered by introducing appropriate source terms in the gas phase equations. The high-lights of the present stochastic model are the computation of non-uniform driving fluid velocities, varying as a function of time, based on Markov chains, within a turbulent eddy, and the crossing trajectory effect. Also, this model is validated for turbulent jet flows laden with particles. The k-epsilon model for the gas flow and the stochastic crossing trajectory simulation (CTS) model for the gas-particle flow are validated with the existing experimental data reported in the literature. The results of the investigation show that the gas-phase turbulent kinetic energy, shear stress, length scales, jet spread and entrainment rates are decreased from their clean jet values as a result of the increased mass loading and size of the particles.