喷射方式对煤油超声速燃烧性能影响的数值研究

Numerical Investigation on Effects of Injection Mode on Supersonic Combustion of Kerosene

关键词:  喷射方式  串联凹腔燃烧室  总体性能  穿透深度  壁面静压  数值研究

Key words:  Injection mode  Staged-cavities combustor  Overall performance  Penetration depth  Wall static pressure  Numerical study

摘要:

为了优化超燃冲压发动机燃料喷注系统，提高燃烧性能和发动机可靠性，基于串联凹腔燃烧室构型，对不同燃料喷射方式下液态煤油超声速燃烧进行了三维数值研究，着重分析了壁喷与环喷两种燃料喷射方式对燃烧室性能的影响，并与试验测得的壁面静压数据进行了对比。研究结果表明，环喷改善了掺混效果，使燃料在流道中分布均匀，使其燃烧效率比壁喷提高了4.36%；两种喷射方式下沿程总压损失基本相当，在出口处总压损失了约50%；在第二排喷点下游，环喷得到的CO₂分布范围比壁喷大，且更均匀，体现了其促进燃烧的特性；环喷因燃料动压比较壁喷的小，故其燃料穿透深度比壁喷小。综合来看，建议在相同的燃料当量比下，选择壁喷方式，以简化燃料喷注系统，提高发动机的可靠性。

Abstract:

In order to optimize fuel injection system in a scramjet engine and improve combustion characteristics and engine reliability，three-dimensional numerical investigation on supersonic combustion of liquid kerosene in different injection modes based on staged-cavities module has been carried out. It is analyzed that wall injection and loop injection have some influence upon the combustor performance. Static pressure predicted by numerical method is compared with experimental data. The results show that loop injection improves mixing characteristics through uniform distribution of fuel in the combustor. Hence，the combustor efficiency of loop injection increased by 4.36% compared with wall injection. The total pressure loss of the two injection modes along the combustor length is almost the same and it loses 50% in the combustor outlet. At the downstream of the second injection ports，range of CO₂ from loop injection is bigger and more uniform than that of wall injection，which indicates that the former can enhance combustion. However，the penetration depth of loop injection is lower than that of wall injection due to small dynamic pressure ratio for the former. In general，it is suggested that wall injection should be chosen to simplify fuel injection system and increase engine reliability at the same fuel equivalence ratio.