An Experimental Study of Multiple Jets Directed Normally to a Cross-Flow

Abstract

Experiments were conducted to study the flow of air jets from a row of identical orifices equally spaced across the floor of a duct which carried an initially uniform airstream. As the pitch of the jets was increased the rate of decay of the jet velocity increased steadily and the penetration of the jets, after initially decreasing, passed through a minimum at a pitch of about four orifice diameters and then increased. This minimum penetration was much less than that of a single jet. Circulation occurred in the lee of the jets when their pitch was less than about three orifice diameters, if the jet-to-cross-stream momentum ratio was high enough. The amount of circulation increased as the jet pitch was reduced and as the momentum ratio was increased.