2016 Volume 59 Issue 3 Pages 134-141
Characteristics of co-flowing jets at subsonic and correctly expanded sonic Mach numbers were investigated numerically for three different lip thicknesses namely, 0.2Dp, 1.0Dp and 1.5Dp (where Dp is the exit diameter of the primary nozzle which is 10 mm). Comparisons of numerical flow-field characteristics were made with experimental data. Lip thickness is defined as the thickness of the wall separating primary jet and the secondary jet. It has been found that co-flow with 0.2Dp lip thickness retards the mixing of the primary jet, leading to potential core elongation. For 1.0Dp and 1.5Dp lip thickness, the presence of lip thickness creates a recirculation zone between the primary jet and the secondary jet, which increases turbulence intensity in the near-field region of the co-flowing jet thereby influencing the properties in the near-field, such as potential core length reduction, static pressure rise, etc. Variation in Mach number has less significance in the flow-field characteristics of co-flowing jet.