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采用直接数值模拟DNS的方法对受损伴流湍流氢气射流火焰进行了数值模拟,采用16步的氢气燃烧详细化学反应机理,冷的高速H2/N2燃料射流喷入热的低速伴随流,伴随流由贫燃氢气预混火焰燃烧产生,温度1045K,氧量较低.化学反应源项由主程序在每一时间步长内动态调用CHEMKIN库函数获得.计算采用消息传递MPI的并行计算方法,采用12颗CPU在并行计算机上完成.作为与实验对比的Faver平均结果由DNS瞬态结果做长时间的统计平均后获得.火焰中涡结构的卷起以及发展过程均能很好地被捕捉,可以观察到同旋向涡结构之间的相互吸引和反旋向涡结构之间的相互排斥过程,伴随射流两侧涡结构彼此复杂的吸引、合并、挤压和撕裂过程,湍流拟序结构由最初的轴对称模式开始向非对称模式演化.流场中5.67ms时刻瞬态的H,OH和H2O分布,表征了燃料射流自点燃过程中的详细火焰结构.计算中获取的火焰抬升高度为9d~11d,与实验结果相吻合.计算发现由OH和H粒子表征的火焰锋面中,在火焰锋面转角位置,燃烧过程得到强化,可能与火焰面的拉伸以及较长的停留时间有关.从湍流强度的分布曲线来看,火焰的传播应该是从两侧向中心发展的.这里的DNS结果可以作为今后发展更准确通用湍流燃烧模型的参考.
The direct numerical simulation of DNS was used to simulate the turbulent hydrogen jet flames with impaired turbulent flow. The 16-step hydrogen combustion detailed chemical reaction mechanism was used. The cold high-velocity H2 / N2 fuel jet was injected into the hot low- Produced by premixed flame combustion of lean burn hydrogen at a temperature of 1045K, the oxygen content is low.The chemical reaction source term is obtained by the main program dynamically invoking the CHEMKIN library function in each time step Calculating the parallel calculation method using message passing MPI, Twelve CPUs were completed on a parallel computer.The average Faver results as a comparison with the experimental results were obtained from the statistical averages of DNS transient results over a long period of time.The windup and development of the vortex structures in the flame were well captured and It is observed that the mutual attraction between the vortex structures and the anti-vortex structures are mutually exclusive. With the complicated vortex attraction, merging, squeezing and tearing processes on both sides of the jet, the turbulence structure consists of The initial axisymmetric mode began to evolve toward an asymmetric mode.The distribution of H, OH and H2O transient at 5.67 ms in the flow field indicated the detailed flame structure of the fuel jet during self-ignition. The results show that the flame front expressed by OH and H particles is enhanced at the front of the flame front, which may be related to the elongation of flame surface and The long dwell time is related to the distribution of turbulence intensity, and the propagation of flame should be from two sides to the center. The DNS results here can serve as a reference for developing a more accurate and generalized turbulent combustion model in the future.