Journal of Fluid Mechanics



Structure of a particle-laden round jet


Ellen K.  Longmire a1 and John K.  Eaton a2
a1 Department of Aerospace Engineering and Mechanics, University of Minnesota, Minneapolis, MN 55455, USA
a2 Department of Mechanical Engineering, Stanford University, Stanford, CA 94305, USA

Article author query
longmire ek   [Google Scholar] 
eaton jk   [Google Scholar] 
 

Abstract

The interaction of solid particles with the temporal features of a turbulent flow has direct relevance to problems in particle and spray combustion and the processing of particulate solids. The object of the present study was to examine the behaviour of particles in a jet dominated by vortex ring structures. An axisymmetric air jet laden with 55 μm glass particles was forced axially with an acoustic speaker to organize the vortex ring structures rolling up in the free shear layer downstream of the nozzle exit. Visualization studies of forced and unforced flow with Reynolds number of the order of 20000 were completed using a pulsed copper vapour laser. Instantaneous photographs and videotapes of strobed forced flow show that particles become clustered in the saddle regions downstream of the vortex rings and are propelled away from the jet axis by the outwardly moving flow in these regions. Phase-averaged spatial distribution of particle number density computed from digitized photographs and phase-averaged particle velocity measurements yield further evidence that local particle dispersion and concentration are governed by convection due to large-scale turbulence structures. The large-scale structures and convection mechanisms were shown to persist for particle-to-air mass loading ratios up to 0.65.

(Published Online April 26 2006)
(Received February 7 1991)
(Revised July 19 1991)



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