Experimental and numerical studies of co-flowing jets with finite lip thickness and varying bypass ratio

Abstract

ABSTRACT The study aims the effect of finite lip thickness and bypass ratio on subsonic and correctly expanded sonic co-flowing jet. The co-flowing jets characteristics were studied for two different lip thicknesses at subsonic Mach 0.6, 0.8, and sonic Mach 1.0 by varying the bypass ratio also the co-flowing jet area. The lip thickness considered for the study case is 1.0Dp and 1.5Dp (Dp – primary nozzle diameter is 10 mm). For experimental setup, the co-flowing duct area was varied the secondary inlet with 4 mm and 5 mm holes. Axial Pitot static tube survey was conducted experimentally. The numerical simulations were also carried by commercial code FLUENT- 6.3.2 for solving the RANS equations using Spalart–Allmaras turbulence model. The flow field has been visualised using numerical contours. The results indicate that for lip thickness 1.0Dp and for low bypass ratio, potential core seems to be thicker. Similar behaviour is observed in 1.5Dp lip thickness. On the other side, for both the lip thickness, 1.0Dp and1.5Dp, as the bypass ratio increases a recirculation zone occurs in the near field region and it becomes dominant. For bypass ratio 6.4 and 1.0Dp lip thickness, the recirculation zone exhibits an outer and an inner vortex.