Particle mixing in free shear flows

• Published in: Progress in energy and combustion science Vol. 14; no. 3; pp. 171 - 194
• Main Authors: Crowe, C.T., Chung, J.N., Troutt, T.R.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 1988; Elsevier Science
• Subjects: Applied sciences; Combustion. Flame; Energy; Energy. Thermal use of fuels; Exact sciences and technology; Theoretical studies; Theoretical studies. Data and constants. Metering; Turbulence; Turbulent flow; Digital simulation; Theoretical study; Combustion; Droplet; Vortex; Dispersion; Turbulence structure
• ISSN: 0360-1285; 1873-216X
• DOI: 10.1016/0360-1285(88)90008-1

The mixing of particles or droplets in free shear layers is encountered in a variety of combustion systems and industrial applications. Free shear layers are characterized by large scale vortical structures which evolve and interact with time. These vortex structures can play a major role in particle or droplet dispersion. It has recently been postulated that the organized rotating motion of the large-scale structures can enhance the dispersion of intermediate size particles. This paper first reviews the currently-accepted mechanisms and models for particle dispersion in homogenoue, isotropic turbulence and addresses the difference between such flows and free shear layers. The essential features of free shear flows are then described and experiments on particle dispersion in free jets and mixing layers are reviewed. Numerical models which have been developed for particle dispersion in free shear layers, such as plane mixing layers, jets and wakes, are outlined and the results are interpreted in light of the postulated physical model. Both experimental results and numerical simulations strongly imply that particle dispersion in free shear layers is controlled by the motion of large scale vortex structures.