燃烧室构型对固体燃料超燃冲压发动机自点火的影响

数值研究了PMMA（聚甲基丙烯酸甲酯）在带凹腔的固体燃料超燃冲压发动机燃烧室中的瞬态自点火机理以及燃烧室构型对自点火的影响.基于求解非定常二维轴对称RANS（Reynolds-averaged Navier-Stokes）方程建立数值模型，湍流模型采用SST（shear stress transport） k-ω模型，燃烧模型采用有限速率/涡耗散模型.结果表明:反应物在凹腔提供停留时间内，产生的化学反应热能够持续积累并提高，使得反应气体达到点火温度时，燃烧室能够实现自点火.凹腔长度、凹腔直径、收敛角和平直段直径是燃烧室构型中影响自点火的主要因素.并提出了一种阶梯式凹腔构型，用于增强自点火性能. 

Influence of combustor shape on self-ignition in solid fuel scramjet

The transient self-ignition mechanism of PMMA (polymethylmethacrylate) and the effect of combustor shape on self-ignition in solid fuel scramjet with cavity were simulated numerically. An unsteady two-dimensional axisymmetric RANS (Reynolds-averaged Navier-Stokes) equation, SST(shear stress transport) k-ω turbulent model, finite-rate/eddy dissipation reaction model were solved numerically. Main conclusions are as follows: the reactants reach the ignition temperature when the heat of reaction accumulates and increases continuously within the residual time provided by the cavity, so the self-ignition is permitted in solid fuel scramjet. The cavity length, cavity diameter, convergence angle and the cylindrical section diameter of the combustor are the main influential factors to the self-ignition. A step type cavity is suggested to enhance the self-ignition performance.