2019/11/15 by Mohammad Rezay Haghdoost, Haghdoost, Mohammad Rezay, Daniel Edgington-Mitchell +7 · 1 citation
Engineering · #Combustion and Detonation Processes #Computational Fluid Dynamics and Aerodynamics #Plasma and Flow Control in Aerodynamics
paper · pdf · doi:10.48550/arxiv.1911.06530
The dynamic evolution of a highly underexpanded transient supersonic jet at\nthe exit of a pulse detonation engine is investigated via high-resolution\ntime-resolved schlieren and numerical simulations. Experimental evidence is\nprovided for the presence of a second triple shock configuration along with a\nshocklet between the reflected shock and the slipstream, which has no analogue\nin a steady-state underexpanded jet. A pseudo-steady model is developed, which\nallows for the determination of the post-shock flow condition for a transient\npropagating oblique shock. This model is applied to the numerical simulations\nto reveal the mechanism leading to the formation of the second triple point.\nAccordingly, the formation of the triple point is initiated by the transient\nmotion of the reflected shock, which is induced by the convection of the vortex\nring. While the vortex ring embedded shock move essentially as a translating\nstrong oblique shock, the reflected shock is rotating towards its steady state\nposition. This results in a pressure discontinuity that must be resolved by the\nformation of a shocklet.\n