Particle/Vortex Interactions in Free and Impinging Air Jets

摘要

Particle-laden gas jets with Reynolds number of order 20000 were forced at fixed frequencies in order to excite periodic vortex ring structures. Particle-to-air mass loading ratio was varied from 4% to 50%, and the flow behavior was documented by flow visualization, number density measurements, and particle and gas velocity measurements. The experiments showed that a Stokes number based on particle inertial and vortex time scales was important in determining the degree of particle clustering and the rate of particle dispersion in free jets. The same Stokes number determined the degree of lag occurring between particles and vortices in the stagnation zone of impinging jets. Vortex rings were found to persist in the free jet when the mass loading ratio was increased to 50%. However, PIV measurements demonstrated that downstream of the stagnation zone in impinging jets, vortices were weakened by mass loading ratios of only 4%.