A Comparison of Classical and Pulsating Jets in Crossflow at Various Strouhal Numbers

Abstract

Investigation of the classical and pulsating jet in crossflow (JICF) at a low Reynolds number (Re = 100) has been performed by the LES method based on varied velocity ratios (r= 1~4). Time-averaged particle trajectories are compared in the classical and pulsating JICF. The formation mechanism and the corresponding flow characteristics for the counter-rotating vortex pair (CRVP) have been analyzed. An unexpected “vortex tail” has been found in the JICF at higher velocity ratio due to the enhanced interactions indicated by the increased jet momentum among the CRVP, upright vortices, and shear layers. The analysis of time-averaged longitudinal vorticity including a coupling mechanism between vortices has been performed. The returning streamlines appear in the pulsating JICF, and two extra converging points emerge near the nozzle of the jet at different Strouhal numbers. The temperature profiles based on the iso-surface for the classical and pulsating JICF have been obtained computationally and analyzed in detail.

Lateral ventilation performance for removal of pulsating buoyant jet under the influence of high-temperature plume

“…34 Some scholars compared the velocity distribution of an unsteady jet with that of a steady jet and confirmed that the flow field distribution of a pulsating jet is significantly different from that of a steady jet. 35–39 The previous research refers to the flow mechanism of a unsteady jet (or a plume), only few experts studied the flow characteristic of the unsteady flow under the effect of ventilation system. Huang et al., 40,41 through a reduced-scale experiment, studied the interaction between the simplified unsteady buoyant jet and the local exhaust flow.…”