Shape effect of cavity flameholder on mixing zone of hydrogen jet at supersonic flow

Cavity flameholder is known as an efficient technique for providing the ignition zone. In this research, computational fluid dynamic is applied to study the influence of the various shapes of cavity as flameholder on the mixing efficiency inside the scramjet. To evaluate different shapes of cavity flame holder, the Reynolds-averaged Navier-Stokes equations with (SST) turbulence model are solved to reveal the effect of significant parameters. The influence of trapezoidal, circle and rectangular cavity on fuel distribution is expansively analyzed. Moreover, the influence of various Mach numbers (M = 1.2, 2 and 3) on mixing rate and flow feature inside the cavity is examined. The comprehensive parametric studies are also done. Our findings show that the trapezoidal cavity is more efficient than other shapes in the preservation of the ignition zone within the cavity. In addition, the increase of free stream Mach number intensifies the main circulations within cavity and this induces a stable ignition zone within cavity.