Movement of Small Spheres in a Plane Mixing Layer

Abstract

Experiments were performed in a two-phase, two free-stream plane mixing layer to study the behavior of heavy spheres in an intermittent shear flow. Particles with three different diameters were employed in these experiments. Comparisons between data on streamwise and transverse components of particle and gas velocities are presented. These data, as well as flow visualization images, suggest that the ratio of the particle time constant τ_p and the large-scale eddy turnover time plays an important role in the cross-stream transport of a heavy dispersed phase. When the τ_p/τ was approximately on the order of 1, heavy particles began to move with gas flow. There exists movement of heavy spheres back toward the particle feed stream. The transverse component of large-particle turbulent velocity, v_p', in the interior of the layer was observed to be significantly smaller than the corresponding streamwise component, u_p' <v^'2>/<u^'2> of the particle reaches an asymptotic value, 0.2, around the high-speed side of the mixing layer.