Flame stability optimization of cavity primary air-jet form in an augmentor

Abstract

A trapped vortex cavity with a radial V-gutter flameholder is adopted to expand the flame stability of an augmentor. The improvement of flame stabilization limits is achieved experimentally by replacing the traditional slotted air-jet with the discrete-hole air-jet. The atomization characteristics of the air-assisted multi-point injector and the numerical fluid-structure are conducted to explain the results. Results indicate that a remarkable enhancement of the flame stability with discrete-hole air-jet is obtained in all conditions, while the slotted air-jet for the cavity leads to a failed ignition at 343 K except for the Mach number of 0.3. As the same passing area of the air-jet, the larger the aperture of the discrete hole, the better the flame stabilization performance. An increasing trend of lean blowout equivalence ratio is contributed by the increased Mach number. Whereas, the Mach number growth will lead to a reduction of lean ignition equivalence ratio at 343 K and 473 K, and a downward parabola is observed at 573 K. Eventually, the optimal flame stability performance is achieved in by the larger discrete space distance, which promotes the fuel/air mixture with the help of the recirculation zones between discrete holes.