Experimental Study of the Formation and Evolution of Gas Jets in Supersonic Combustion Chambers

A simple and efficient flow field visualization method (based on shadow imaging) was applied in a direct-connect test to explore the influence of the momentum flux ratio and the jet angle on the formation and evolution of nitrogen jets in supersonic combustion chambers. The test setup adopts a rectangular flow passage to simulate a flight condition with Mach number of 6 and altitude of 25 km. The experimental results showed that (a) the flow field visualization method adopted in this paper can clearly register the formation and evolution of the shock wave structure in the flow field and the windward shear vortex on the jet surface. (b) The evolution process of the windward shear vortex is significantly affected by the jet angle. In particular, the stretching position of the windward shear vortex changed when the jet angle was obtuse. (c) The bow shocks showed local distortion due to the periodic generation of large-scale shear vortexes. (d) Under the working conditions of the test, the largest instability of the flow field was found for a jet angle of 120 degrees. This work provides, on one hand, the experimental basis for clarifying the formation and evolution mechanism of transverse gas jets, and on the other, valuable data that can be used to validate numerical simulations.

Automated summary

In this paper, a simple and efficient flow field visualization method based on shadow imaging was applied in a direct-connect test to investigate the influence of the momentum flux ratio and jet angle on the formation and evolution of nitrogen jets in supersonic combustion chambers. The experimental results showed that the method used in this study can clearly capture the formation and evolution of shock wave structures and windward shear vortices. Moreover, the evolution of windward shear vortices is significantly affected by the jet angle, especially when the angle is obtuse.