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