Effect of Eccentricity on Co-flow Jet Characteristics

Effect of eccentricity on jets delivered from a primary nozzle surrounded by secondary flow is studied experimentally. The eccentricity is achieved by offsetting the annular spacing of the co-flow passage, surrounding the center nozzle generating the primary jet. This is achieved by making a base plate with its center which is offset by 2 mm in the downward direction with the center of inner nozzle. The studies have been carried out in possible flow regimes of jet exiting from a convergent nozzle like subsonic and correctly and underexpanded sonic conditions. The experiments were carried out for primary nozzle exit Mach numbers of 0.3, 0.5, 0.8 and 1.0 at correct expansion. The studies in underexpanded regime were conducted for nozzle pressure ratios (NPR) of 3 and 4. The eccentricity in the co-flow jet leads to 38% reduction in the supersonic core length at NPR 3 and 60% at NPR 4 in comparison with concentric co-flow configuration. The eccentricity also leads to early mixing of co-flowing jet.