Abstract: To study the effects of quasi-DC discharge plasma on the combustion flow field of ethylene/air in a scramjet combustor under the low equivalent ratio，a quasi-DC discharge plasma filament actuator electrodes crossed upstream of the cavity and bottom of the front wall has been settled. Under the different plasma actuation intensity，the effect of plasma on pressure distribution around the rear wall，the total pressure loss of combustion chamber，the combustion efficiency of ethylene/air and the distribution of water in combustion chamber are nu.merically studied.The results show that，the higher the plasma actuator intensity，the stronger the stability of the pressure field near the rear wall of the cavity. The total pressure loss at the combustor exit slightly increased with the presence of the plasma，the maximum loss increased by 1.9%. The average combustion efficiency of ethylene/air increased by 1.77 times in the combustion chamber，with the increase of the excitation intensity，the combustion efficiency increased first and then decreased. The plasma ameliorates the distribution of water in the combustion chamber，and the water distribution is wider and the combustion is more complete of the interior cavity.

Key words: Scramjet engine； Quasi-DC discharge； Plasma； Mathematical computation； Supersonic combustion

摘要： 为研究低燃空比条件下，准直流放电等离子对超燃燃烧室中乙烯燃烧流场的影响，在凹腔上游以及底部前壁面处布置电极产生等离子体，通过数值模拟方法，分析了不同等离子体激励强度下，燃烧室凹腔后缘附近压力分布、燃烧室总压损失、乙烯燃烧效率和燃烧室中水的分布情况。研究结果表明:准直流放电等离子体激励强度越高，对凹腔后缘附近压力场稳定能力越强。等离子体的存在，使得燃烧室出口总压损失微弱增加，损失最大值增加 1.9%。燃烧室中乙烯燃烧效率平均提高 1.77倍，随着激励强度的提高，燃烧效率呈现先增高后降低的趋势。等离子体改善了燃烧室中水的分布，凹腔内部产物分布范围更广、燃烧更加充分。

关键词: 超燃冲压发动机；准直流放电；等离子体；数值计算；超声速燃烧