在课题组前期工作的基础上，对一马赫数为1．2的三维超音速氢气射流抬升火焰进行了直接数值模拟研究，其中空间离散采用波带优化的四阶WENO格式，时间积分采用带有TVD性质的三步三阶龙格库塔格式，边界条件采用了无反射特征边界条件，总的计算网格数达到9．75亿。结果表明：超音速射流氢气燃烧火焰可分为根部层流状的高温高热量释放率稳燃区、高度褶皱的湍流剧烈混合区和远场燃烧区。火焰自燃稳燃点出现在喷口附近的x／D=0．86处，对应着最易反应混合分数。在此下游，预混燃烧和扩散燃烧两种模式同时存在，其中在剧烈混合区和远场区火焰以扩散燃烧为主，但在火焰根部的局部区域预混燃烧热量释放率达到35％左右。
Based on previous work of our group, direct numerical simulation of a three-dimensional supersonic hydrogen jet lifted flame with a Mach number of 1.2 was performed. The fourth-order bandwidth-optimized WENO scheme was used for spatial discretization, and the third-order TVD Runge-Kutta multistage method was used for time integration. The non-reflecting characteristic boundary conditions were applied to describe the computational boundary conditions, and the total computational grid points reach to 975 million. The results show that the supersonic jet hydrogen combustion flame can be divided into three regions, namely a stable laminar flame base with high temperature and high heat release rate, a violent turbulent mixing region with highly corrugated flame surface, and a far field flame region. The auto-ignition stabilization point of the flame appears at x/D=0.8 close to the nozzle, corresponding to the most reactive mixture fraction. In the downstream region, both premixed and non-premixed flames coexist in the jet. In the violent mixing region and far field, ilon-premixed flames dominate. But in the local region near the flame base, the premixed flame may contribute 35% to the total heat release rate.
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