Comparison of atlas ground based plume imagery with chemically reacting flow solutions

High spatial resolution, multi-spectral images have recently been obtained of rocket plumes in-flight. Spatial resolution of one-meter or less in the ultraviolet and mid wavelength infrared spectral regions can provide information about the complex plume structure which varies as the rocket traverses different altitudes. The data is unique in that it provides one of the first detailed shock structure of a rocket plume in flight. The paper presents examples of Atlas plume data and discusses some of its unique aspects. To explain the major features of the data, axisymmetric and threedimensional multi-nozzle plume flows of the Atlas rocket were investigated with a three-dimensional Navier-Stokes solver. A 15 km altitude case where the plume is moderately underexpanded and a 40 km altitude case where the plume is highly underexpanded were examined because of their differing plume structure. The plume flowfields were examined to determine the underlying physics and the main parameters that affect the optical radiation. The computed results are compared with measured field values.