双排凹腔燃烧室释热区转移过程中的特性研究

Characteristics of combustor with dual-rows cavities during heat release zones transferring

关键词:  双排凹腔  燃烧室  稳焰  超声速燃烧  火焰不对称

Key words:  Dual-rows cavities  Combustor  Flame stabilization  Supersonic combustion  Flame asymmetry

摘要:

为探究多凹腔燃烧室前后排凹腔释热区转移过程中的演化特性，利用直连台在Ma=3.0条件下进行总当量比（φT）不变，前排凹腔当量比（φ1）增加，后排凹腔当量比（φ2）降低的试验。φ1较低时，前排凹腔为凹腔剪切层稳焰，后排凹腔为射流尾迹稳焰。当φ1增加到一定值，前排凹腔火焰由凹腔剪切层稳焰转换为射流尾迹稳焰，致使沿程压力出现突变。由于φ1较低，当地释热不足以维持火焰为射流尾迹稳焰，前后排凹腔燃烧耦合使得前排凹腔火焰在两种稳焰模式之间切换。φ1继续增加，前排凹腔的释热使火焰稳定在射流尾迹稳焰。之后φ1继续增加，前排凹腔火焰出现不对称的情况，这种不对称是随机的，且随着当量比的增加变得更加明显且持续时间更长。φ1继续增加使得前排凹腔出现火焰闪回现象。

Abstract:

To explore the evolution characteristics of the transfer process of the heat release area in the first and second rows of cavities of the combustor， under the condition of Ma=3.0 inflow， the direct-connect facility was used to carry out the experiment in which the total equivalence ratio （φT） remained unchanged， the injection equivalence ratio of the first injection point （φ1） gradually increased， and the injection equivalence ratio of the second injection point （φ2） gradually decreased. When φ1 is low， the flame in the first row of cavities is the cavity shear-layer stabilized combustion， and the flame in the second row of cavities is jet-wake stabilized combustion. When φ1 increases to a certain extent， and the flame stabilization mode of the first row of cavities transitioned from the cavity shear-layer stabilized combustion to the jet-wake stabilized combustion， resulting in an abrupt change in the pressure distribution. Since φ1 is relatively low， the local heat release is not enough to maintain the first row of cavities as the jet-wake stabilized combustion. Under the coupling effect of the first and second cavities， the flame will switch back and forth between the two flame stabilization modes. As φ1 continues to increase， the heat release of the first row of cavities can make the flame of the first row of cavities stabilized in the jet wakes. As φ1 continues to increase， the flames on the upper and lower walls of the first row of cavities will be asymmetrical， which is random. This asymmetry will become more pronounced and last longer as the equivalence ratio increases. Finally， φ1 increases to a certain extent， the flame flashback phenomenon occurs.