Gas-droplet turbulent velocity correlations and two-phase interaction in an axisymmetric jet laden with partly responsive droplets

The effect of fluid-particle interaction on the development of an axisymmetric jet laden with partly responsive droplets is discussed in this paper. Measurements up to 40 diameters were obtained by using phase Doppler and laser induced fluorescence technique (combining both techniques provides the mass concentration of liquid per size class). Comparison of the mean gas velocity fields with and without drops shows clearly the expected effects of the dispersed phase on the carrier phase, known as "two way coupling". Statistics of the velocity of the fluid "seen" by the particles have been calculated after temporal reconstruction of the turbulent signal of the continuous phase. The fluid-particle correlations are presented and used to analyse the radial evolution of the particle stresses. We show that the anisotropy of the drop fluctuation motion is large and associated with production mechanisms, via interaction with mean particle velocity gradients. Finally the attenuation term, which complements the conventional transport equation of the turbulent kinetic energy for single-phase flow, is calculated. Radial profiles are presented (X = 20d(0)) and compared with an estimation usually found in the literature, when neglecting the fluid-particle correlations. The results clearly show that such estimation really overestimates the magnitude of the term responsible for the direct turbulence attenuation by the particles. (C) 2003 Elsevier Science Ltd. All rights reserved.