反压对隔离段激波串结构的影响

Influence of back pressure on shock train structure in isolator

采用不同的无黏通量格式与湍流模型组合对轴对称圆截面隔离段进行了数值计算,选取与试验结果最匹配的组合研究隔离段在反压作用下的流场结构及参数特性.对不同反压下的独立隔离段模型和隔离段燃烧室模型进行了三维模拟,分析了隔离段反压比对其流场结构、出口参数及其中激波串形态的影响.针对该轴对称隔离段提出了其可承受的极限反压.比较了冷态均匀反压与燃烧诱导反压下的隔离段流场.结果表明:无黏通量格式与湍流模型的选择影响着激波串的形态和长度,对于隔离段数值模拟十分关键;隔离段出口参数受反压影响,出口处在激波串区域时,附近截面上静压分布的不均匀性较大,出口处在混合区时压力分布则相对更均匀,激波串发展程度影响隔离段出口压力均匀性;对于该圆截面隔离段及燃烧室,直接给定均匀的平面冷态反压所产生的激波串与燃烧反压下的激波串在结构形态和起始位置上未见明显差异.

In order to investigate the characteristics of axisymmetric cylind under different back pressures, the flow field of the isolator was simulated with rical isolator different in- viscid flux schemes and turbulence models. Compared with the experimental data, the most suitable model and scheme were chosen. Three dimensional simulations of the isolator and combustor were employed to study the flow field structure, exit parameter and shock train under different back pressure ratios. The limit back pressure was found. The structures of the shock train under two kinds of back pressure were compared. Results show that the in- viscid flux scheme and turbulence model, which are critical for the isolator simulation, have a significant impact on the structure and length of the shock train. The parameter of the iso-lator exit is affected by the back pressure. When the exit of the isolator is in the mixing re-gion, the static pressure distribution is more uniform. And when the exit is in the shock train region, the pressure is non-uniform. For this axisymmetric cylindrical isolator and com bustor, there is no obvious difference on structure and initial position of the shock trains re-spectively induced by the combustion back pressure and cold back pressure.