Experimental and numerical investigation of an axisymmetric supersonic jet

A comprehensive study of a steady axisymmetric supersonic jet of CO2, inclu ding experiment, theory, and numerical calculation, is presented. The exper imental part, based on high-sensitivity Raman spectroscopy mapping, provide s absolute density and rotational temperature maps covering the significant regions of the jet: the zone of silence, barrel shock, Mach disk, and subs onic region beyond the Mach disk. The interpretation is based on the quasi- gasdynamic (QGD) system of equations, and its generalization (QGDR) conside ring the translational-rotational breakdown of thermal equilibrium. QGD and QGDR systems of equations are solved numerically in terms of a finite-diff erence algorithm with the steady state attained as the limit of a time-evol ving process. Numerical results show a good global agreement with experimen t, and provide information on those quantities not measured in the experime nt, like velocity field, Mach numbers, and pressures. According to the calc ulation the subsonic part of the jet, downstream of the Mach disk, encloses a low-velocity recirculation vortex ring.