  In this work, supersonic premixed H2/air combustion stabilised by a cavity
flame-holder in a model scramjet combustor with a Mach 1.5 inflow is studied
via direct numerical simulations. By applying turbulent and laminar inlet
condition separately, we compare the flame stabilisation characteristics
between these two cases to study the effect of inflow turbulence. The ignition
and flame propagation process are similar in both cases.After combustion in the
area near the cavity reaches quasi-stationary state, the results show that with
inflow turbulence more robust vortices are developed in cavity shear layer and
near the aft wall, resulting in a thicker reaction zone and larger flame
surface which present more efficient combustion. In addition, the inlet
turbulence enhances the entry of fresh mixture and this further supports flame
stabilisation near the cavity. However, the fully developed cavity shear layer
also leads to greater cavity resistance. As for the flame stabilization, with
inlet turbulence more robust recirculation and stronger mass exchange process
is observed and promote the radical transport. These results give a preliminary
insight into the flame stabilization mechanism. The distribution of progress
variable indicates that the flame stabilized toward products side with
turbulent inlet.
