Study on mixing and combustion performance of a kerosene-fueled dual-cavity configuration scramjet engine

Abstract

On the basis of a wedge-type scramjet engine model, this paper employs experimental and numerical simulation methods to investigate the effects of different injection conditions of liquid kerosene fuel on the combustion characteristics of a scramjet combustor at a Mach number of 8. The findings indicate a distinct separation zone in the cavity of the wedge, where the fuel residence time is longer compared with that in the main flow path. This increased residence time enhances fuel mixing and combustion stability. Between equivalence ratios of 0.24 and 0.64, the combustion reaction intensifies significantly, particularly in the range from 0.24 to 0.54. This intensification coincides with a notable expansion of the reflux zone and a wider subsonic velocity range. With increasing equivalence ratio, the periodicity of wave system oscillations in the combustor also increases, along with the pressure in the concave chamber. Pronounced oscillations in the flow field are observed at equivalence ratios of 0.4 and 0.54, with an oscillation period 5.4 times longer than at a ratio of 0.24. At an equivalence ratio of 0.64, the backpressure causes disturbances in the isolation section, affecting inlet initiation. Additionally, a higher equivalence ratio results in greater total pressure loss. The total pressure loss is highest at an equivalence ratio of 0.64, reaching 82 % of the total inlet pressure, and lowest (76 %) at a ratio of 0.24. The thrust is also correlated with the equivalence ratio, increasing by 22.5 % and 37.5 % at equivalence ratios of 0.34 and 0.4, respectively, compared with a ratio of 0.24. The maximum thrust gain is achieved at an equivalence ratio of 0.5, a 56 % increase over that at a ratio of 0.24 condition. However, at an equivalence ratio of 0.64, there is a notable decline in engine thrust due to significant disruption of the flow field structure within the combustor.