  In this study, we perform a two-dimensional axisymmetric simulation to assess
the flow characteristics and understand the film cooling process in a dual bell
nozzle. The secondary stream with low temperature is injected at three
different axial locations on the nozzle wall, and the simulations are carried
out to emphasize the impact of injection location (secondary flow) on film
cooling of the dual bell nozzle. The cooling effect is demonstrated through the
temperature and pressure distributions on the nozzle wall or, in-turn, the
separation point movement. Downstream of the injection point, the Mach number
and temperature profiles document the mixing of the main flow and secondary
flow. The inflection region is observed to be the most promising location for
the injection of the secondary flow. We have further investigated the effect of
Mach number of the secondary stream. The current study demonstrates that one
can control the separation point in a dual bell nozzle with the help of
secondary injection (Mach number) so that an optimum amount of thrust can be
achieved.
