双支板超燃冲压发动机燃烧特性研究

为研究分级喷注超燃冲压发动机火焰稳定、燃烧状态及火焰传播特性,以双支板超燃燃烧室为基本构型,开展了当量比连续调节试验研究。模拟低飞行马赫数5.5工况,燃烧室入口马赫数为2,总温1436 K,试验表明:燃烧室单独上游喷注熄火当量比为0.19,该值不受下游燃烧的影响;单独下游喷注熄火当量比为0.46,上游火焰会削弱下游当量比变化对壁面压力的影响,并且会使下游熄火当量比值降低。通过调节上游当量比可实现燃烧状态的转换,转换过程存在迟滞。模拟高飞行马赫数6.5工况,燃烧室入口马赫数为3,总温1 899 K,试验表明:随着总温的增加,单独上游喷注可实现点火和稳焰,上游火焰发生抬举,燃烧室抗反压能力增强,可喷注更多燃料。

Combustion performance investigation of a dual-struts scramjet

In order to investigate the flame stabilization, combustion state and flame propagation characteristics of scramjet, based on a dual-struts supersonic combustor with staged injections, experiments with continuously adjusted equivalence ratio were conducted. Experiments with combustor inlet Mach number of 2 and total temperature of 1 436 K were conducted to simulate flight Mach number of 5.5. The results show that when injecting fuel is solely from the upstream strut, the extinction equivalence ratio is 0.19 and it is not affected by the downstream combustion. When injecting fuel is solely from the downstream strut, the extinction equivalence ratio is 0.46, and the effect of downstream equivalence ratio change on wall pressure would be reduced by upstream flame, with which the extinction equivalence ratio would be decreased. Transformation between two combustion states could be realized by adjusting the upstream equivalence ratio, and hysteresis could be observed in the transformation process. Experiments with combustor inlet Mach number of 3 and total temperature of 1 899 K were conducted to simulate flight Mach number of 6.5. The results show that as the total temperature of incoming flow increases, ignition and stable flame can be realized by fuel injection solely at the upstream strut, the upstream flame is lifted, back-pressure capability of the combustor can be strengthened, and more fuel can be injected into the flow.