激波加热超声速燃烧室直连式试验台喷管中的化学非平衡流动

Chemical nonequilibrium flow in nozzle of a supersonic combustor direct-connected test bed with shock heating

为了开展飞行马赫数8和9的超燃冲压发动机直连式试验研究,将中国空气动力研究与发展中心的FD-14激波风洞改造成了激波加热超声速燃烧室直连式试验台。设计了两组喷管,喷管出口马赫数为3.5和4.5,分别用于模拟飞行马赫数8和9的超燃冲压发动机燃烧室入口气流条件。采用Park、Gupta、Dunn/Kang三种纯空气化学反应动力学模型,对马赫数3.5及马赫数4.5喷管中的化学非平衡流动进行了数值模拟研究,并对三种纯空气化学反应模型进行了比较分析。研究结果表明:在喷管收缩段,N2和O2的离解效应显著,而在喷管扩张段,N原子和O原子的复合效应更加显著;马赫数3.5及马赫数4.5喷管出口的NO摩尔分数分别为2.3%~2.57%和4.8%~6.0%,O原子摩尔分数分别为0.04%~0.11%和0.75%~1.25%,N原子摩尔分数几乎为零;在喷管扩张段,流动为典型的"冻结流";三种化学反应模型中,采用Gupta模型时O2和N2的离解程度最大,相应生成的NO及O原子含量更高,但是三个反应模型计算获得的各个组分在喷管内部及喷管出口截面的分布规律是一致的。

In order to carry out direct-connected tests of scramjet with flight Mach number 8 and 9,the shock tunnel named FD-14 of China Aerodynamics Research and Development Center was reconstructed to be a supersonic combustor direct-connected test bed with shock heating.Two nozzles were designed for the direct-connected test bed and their outlet Mach numbers are3.5 and 4.5,which can simulate the combustor entrance conditions of scramjet with flight Mach number 8 and 9,respectively.Using three different chemical reaction models of pure air developed by Park,Gupta and Dunn/Kang,chemical nonequilibrium flows in Mach number 3.5 and 4.5 nozzles are studied by numerical simulation.Besides,differences between the three chemical reaction models are compared and analyzed.Calculation results indicate that,in contraction section of the two nozzles,dissociations of N2 and O2 are obvious,but in expansion section of the two nozzles,recombinations of N and O are more remarkable.On the outlet planes of Mach number 3.5 and 4.5 nozzles,mole fractions of NO are respectively 2.3%~2.57% and 4.8%~6.0%,mole fractions of O are respectively 0.04%~0.11% and 0.75%~1.25%,and mole fractions of N are both nearly zero.In the expansion section of two nozzles,the flows are freezing.Among three chemical reaction models,the dissociation degrees of O2 and N2 are maximum by using Gupta chemical reaction model,which leads to the maximum mole fractions of NO and O on nozzle outlet.However,distribution laws of each component are same in nozzles and on outlet planes of nozzles acquired from three chemical reaction models.