Effects of vortices on particle motion in a stagnation zone

Ellen K. Longmire, Steven L. Anderson

Research output: Contribution to conferencePaper

Abstract

A round air jet with Reynolds number of 21000 was forced with an acoustic speaker to generate ring vortices of repeatable strength and frequency (f). The jet impinged normally on a circular glass plate located five diameters downstream of the nozzle exit. Particles with inertial time constants of 1.7 and 7 ms were added to the flow upstream of the jet plenum, and the evolving flow structure in the stagnation region was investigated. Particles with larger time constants yielded significant particle concentrations in the stagnation zone throughout the forcing cycle. Concentrations were the highest slightly before vortex ring impingement. In general, particles with smaller time constants yielded greater dispersion and lower concentrations in the stagnation zone. Concentrations were minimized 90° after vortex ring impingement. PIV measurements reveal that particle rebounding is important in all cases studied. The rebound height, which is dependent on the mean Stokes number Stm = τpUo/D, affects the subsequent radial acceleration and resulting residence time in the stagnation zone. The ratio of particle to vortex time scales, St′ = τpf, affects the degree to which particle/vortex combinations become dissociated or reorganized.

Original languageEnglish (US)
Pages95-101
Number of pages7
StatePublished - Dec 1 1995
EventProceedings of the 1995 ASME/JSME Fluids Engineering and Laser Anemometry Conference and Exhibition - Hilton Head, SC, USA
Duration: Aug 13 1995Aug 18 1995

Other

OtherProceedings of the 1995 ASME/JSME Fluids Engineering and Laser Anemometry Conference and Exhibition
CityHilton Head, SC, USA
Period8/13/958/18/95

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    Longmire, E. K., & Anderson, S. L. (1995). Effects of vortices on particle motion in a stagnation zone. 95-101. Paper presented at Proceedings of the 1995 ASME/JSME Fluids Engineering and Laser Anemometry Conference and Exhibition, Hilton Head, SC, USA, .