Effect of increasing bypass ratio on supersonic co-flowing jet with finite lip thickness

•The effect of increasing bypass ratio on a supersonic co-flowing jet with finite lip thickness.•The surrounding jet enhances the wake dominance in the nozzle lip and the length of the supersonic core shortens.•The radial Mach number profiles offer a quantitative representation of different zones in the co-flowing jet. The article presents the investigation on the effect of increasing bypass ratio on a supersonic co-flowing jet with finite lip thickness for a jet exit Mach number of 2.0. Co-flowing jets of differing bypass ratios (BR = ms/mp, where ms and mp are the mass flow rate of secondary and primary jets, respectively) 3.69, 9.0, and 16.0 were employed to explore the impact of high bypass secondary jets on the primary jet. A single-jet BR 0 is used for comparison. The supersonic core lengths of the single jet and the co-flow jet for BR 3.69, BR 9.0, and BR 16.0 were metrics for quantifying the mixing. The surrounding jet enhances the wake dominance in the nozzle lip, and the supersonic core length shortens. High bypass co-flowing jets are extremely efficient at shortening the supersonic core length compared to the low bypass counterpart, and hence, the jet mixing increases. The radial Mach number profiles quantitatively represent different zones in the co-flowing jet. The variation of these zones with bypass ratios highlights the dynamic interaction between the primary and secondary jets. The physical reason for apparent jet mixing and flow categories has been discussed based on considerations about changes in the flow field and shock structure.