台阶和凹腔在固体燃料超燃冲压发动机内自点火性能对比

Difference of self-ignition performance in solid fuel scramjet with step or cavity

数值研究了PMMA在固体燃料超燃冲压发动机燃烧室中的非稳态自点火过程及带台阶或凹腔的燃烧室构型对自点火的影响。数值模型基于求解非定常二维轴对称RANS方程,采用SST k-ε湍流模型,采用有限速率/涡耗散燃烧模型,装药和内流场的耦合传热采用一维导热方程。结果表明,台阶和凹腔火焰稳定器都能实现自点火。带台阶和凹腔的不同燃烧室内自点火过程一致;与采用突扩台阶火焰稳定器相比,凹腔火焰稳定器能够满足更宽的进气条件下的自点火;加入适当长度的凹腔,既可改善点火性能,又可增强总体性能。建议采用凹腔来实现SFSCRJ的自点火。

The self-ignition process of poly-methyl-methacrylate and the effect of combustor shape with step or cavity on self-ig-nition in solid fuel scramjet were simulated numerically.An unsteady,two-dimensional, axisymmetric,turbulent （SST model）,reac-tion （ finite-rate/eddy dissipation reaction model） ,one dimensional heat conduction between the gas and solid fuel grain model was solved numerically.Main conclusions are as follows.Both of step and cavity could establish self-ignition.The self-ignition processes of these two flame-holders are consistent. Self-ignition could be established under a relatively wide range of inlet conditions for cavity compared with step.A cavity with appropriate length enhances not only the self-ignition performance but also the overall performance. Cavity is the advanced flame-holder which can be used for self-ignition in SFSCRJ combustor.