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在来流总温1486K,总压1.6MPa,马赫数2.52的条件下,采用两级串联凹腔构型燃烧室,开展了电火花塞直接点燃航空煤油的试验研究。利用高速摄影相机进行观测,对比了不同煤油喷注方案和点火位置对火核生成和火焰传播的影响。通过上游凹腔前壁面水平喷注煤油、下游凹腔点火的方案可靠性高,在煤油与空气混合气的当量比为0.04~0.063均可实现煤油成功点火和稳定燃烧;串联凹腔构型可以提高点火性能的主要原因有两方面:一是下游凹腔有稳定火焰作用,火焰在边界层内逆流传播实现对上游凹腔的能量反馈;二是煤油蒸发、混合距离长,通过近壁区进入下游凹腔,形成了更为适宜的点火环境。
Under the conditions of the total temperature of 1486K, the total pressure of 1.6MPa and the Mach number of 2.52, a two-stage tandem cavity configuration combustor was used to test the ignition of jet fuel directly by spark plug. Using high-speed photographic camera for observation, compared different kerosene injection program and ignition position on the nucleus formation and flame propagation. Through injecting kerosene horizontally on the front wall of the upstream cavity, the scheme of ignition in the downstream cavity is highly reliable. When the equivalent ratio of kerosene and air mixture is 0.04-0.063, successful kerosene ignition and stable combustion can be achieved. There are two main reasons to improve the ignition performance: First, the downstream cavity has a stable flame, the flame propagation countercurrent in the boundary layer to achieve the upper cavity of the energy feedback; Second, kerosene evaporation, long mixing distance, through the near wall into Downstream cavity, forming a more suitable ignition environment.