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Fig. 5 Contours of LT 7.75 mm for NPR 3: a total pressure, b Mach number, c turbulent kinetic
energy, and d density gradient
contour (Fig. 5b). Visible recirculation zone appears between jets at subatmospheric
region. The secondary jets core orients toward jet centerline. The region between
jets shows a recirculation zone. In CFD analysis, we can capture supersonic nozzle
characteristics but we cannot see subsonic pockets in the co-flow as the mass flow
is less. The turbulent kinetic energy between jets becomes widened and magnitude
increased (10460–14170 m
2 /s
2 ). The shock crossover looks similar between both
jets (which was also confirmed with CTPD) but there is a significant mixing in the
characteristic decay region (Fig. 5c).
The region of high turbulence widens because of wake dominance. Increased
turbulence is observed in the recirculation zone and least turbulence is inside the
potential cones. The turbulence contour shows the progressive nature of jet along
its axis and the shear layer shows the momentum transport. Shear layer is small
at starting and then gets widened. The numerical shadowgraph (density gradient)