  The fuel injection system is the main process in supersonic vehicles. In this
article, injection of fuel jet through a trapezoidal strut in the coaxial
supersonic air stream is investigated. The numerical method is applied for the
simulation of three-dimensional trapezoidal lobe strut in supersonic flow.
Hydrogen gas is injected from the end of the trapezoidal strut injector to
augment fuel mixing and diffusion downstream by intensifying vortices inside
the domain. The power of the vortices varies by the injector velocity and free
stream condition. To simulate our model, RANS equations with the SST turbulence
model are solved. Effects of free-stream velocity and fuel jet total pressure
on fuel distribution and mixing are also investigated. Our results indicate
that fuel mixing enhances about 18% when a rectangular strut is replaced by a
trapezoidal one. An achieved finding disclosed that the strength of vortices is
amplified by the presence of a trapezoidal strut injector.
