The Air Force Research Laboratory has an ongoing effort to develop an accur
ate and efficient computational tool to support the development of advanced
chemical oxygen/iodine laser (COIL) devices. In this study, a series of co
mputational simulations have been performed to provide a better understandi
ng of fluid dynamic phenomena within geometries associated with COIL flowfi
elds. The parallel, implicit unstructured Navier-Stokes code Cobalt(60) was
used. to compute laminar, turbulent, and unsteady Rows of helium within th
e research assessment and device improvement chemical laser (RADICL) nozzle
, Computational results showing details of the jet mixing interaction and t
opological structure are presented. The laminar and turbulent results obtai
ned with Cobalt(60) are in excellent agreement with measured mass Row rates
and surface pressure data obtained from recent cold-how tests performed wi
th the RADICL device. Insufficient experimental measurement prevents the de
termination of whether or nut transition occurs within the injector region.
The laminar time-accurate results indicate small-scale unsteadiness in the
frequency range of 200 kHz downstream of the nozzle throat.