论文部分内容阅读
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 the previous work of the research group, a direct numerical simulation of the uplift flame of a three-dimensional supersonic hydrogen jet with a Mach number of 1.2 was conducted, in which the fourth-order WENO format optimized for wavelength bands was used for spatial discretization, Three-step third-order Runge-Kutta format, boundary conditions using non-reflective feature boundary conditions, the total number of grid computing 975 million. The results show that the flame of supersonic jet hydrogen combustion can be divided into steady zone of high temperature and high heat release rate of root laminar flow, highly turbulent mixing zone with high folds and far-field combustion zone. Spontaneous combustion spontaneous combustion point appears near the nozzle x / D = 0.86 Office, corresponding to the most reactive mixed fraction. In the downstream, the two modes of premixed combustion and diffusion combustion exist simultaneously, of which the flame is dominated by diffusion combustion in the intense mixing zone and the far-field zone, but the release rate of premixed combustion heat is about 35% in the flame root zone.