Experimental and Numerical Study on the Plasma-Laser-Induced Ignition of Strut Stabilizer at Different Locations

Abstract

The minimum ignition equivalence ratio of the strut stabilizer is an important parameter in the design of integrated afterburners. The ignition location significantly affects the ignition equivalence ratio and flame propagation, and therefore, it should be deeply studied. The ignition equivalence ratio and flame propagation at different axial ignition locations downstream of the strut stabilizer are studied in this paper. When the ignition distance is approximately the bluff body trailing edge width, a lower ignition equivalence ratio is required for ignition, and the flame propagates faster through the entire combustion chamber. For different ignition locations, the generated flame kernel at different locations all first propagates to the shear layer. Subsequently, the unilateral flame rapidly extends, ultimately igniting the entire combustion chamber. The flame propagation trajectory depends on the ignition location controlled by the non-reacting flow field and the distribution of kerosene concentration. The flame propagation trajectory mainly includes three paths: (1) the flame kernel is directly downstream the shear layer when the ignition location is close to the tail edge of the stabilizer, (2) the flame propagates upstream into the shear layer in a U-shape when the ignition location is far from the stabilizer but still in the recirculation zone, and (3) the flame propagates upstream into the recirculation zone and shear layer in a U-shape when the ignition location is outside the recirculation zone. In addition, the time for flame propagation to the shear layer is directly related to the ignition performance when the ignition location is within the recirculation zone. If the flame reaches the shear layer in a longer time, there will be more energy loss during the flame propagation process, and the ignition performance will deteriorate. The speed of the flame-trailing edge extension is directly related to the ignition fuel-air ratio, and the downstream extension of the flame is mainly affected by the turbulence velocity in the shear layer.