Air flow and droplet motions produced by the interaction of flat-fan sprays and cross flows

The interaction between the vertical flow induced by downward-pointed spray s and a horizontal cross flow was studied using a boom of overlapping flat- fan sprays in a wind tunnel. Flow patterns were visualized, and droplet flu xes, velocities, and sizes,were measured 2 m downwind of the boom using lin e collectors and a phase-Doppler analyzer, under weak and moderate cross fl ows, in which the ratio of the cross-flow velocity to the maximum air entra inment velocity into the spray,was respectively less and greater than unity . For weak cross flows, the spray was penetrated only in regions of low ent rained air velocity, with downstream droplet fluxes and air velocity maxima corresponding to the spray edges. For moderate cross flows, the spray xas penetrated everywhere across its width. Downstream flax measurements corres ponded to the spray centerline, which is the origin of the highest flux of fine droplets that are "scavenged" by the mean cross flow. Drifting droplet s had diameters less than 100 mu m and were transported passively by the cr oss flow.