The stabilization mechanism of a supersonic lifted jet flame in the heated coflows should be attributed to the competition between autoignition and the propagation of active kernels at the flame base. As a result, the characteristics of the lifted hydrogen jet combustion gradually vary along the axial direction, which have not yet been deeply addressed in the previous studies. Highly-resolved large eddy simulation of a hydrogen jet injection into the air flow is carried out in this paper, the particular emphasis of which is placed on the evolution process of the turbulent structures as well as the flameholding mechanism. To analyze the effect of turbulence on the chemistry, an assumed probability density function method is adopted to close the source term of the governing equations. And the temporal and spatial resolution of the numerical schemes is high enough to capture the unsteady motion inside the supersonic reactive flowfeild. Predicted concentration of some important species agrees well with that measured by the experimental methods, demonstrating the responsibility of numerical results. From the instantaneous images, large eddy simulation reproduces the three-dimensional flowfield generated by the interaction of the inner jet and heated air flow. According to the time-averaged analysis, the combustion flowfield can be divided into three stages, namely the initial mixing, autoignition and subsequent turbulent flame. Evidently, the supersonic reactive flow passes through the transition from autoignition to the partially premixed flame, and the statistical features along the axial direction change correspondingly. Further, the effect of small-scale turbulent fluctuations on the reactive front within the shear layer is analyzed in detail, and the significant founding is propitious to understand the turbulent combustion regime in high-enthalpy conditions.

在加热的气流中超音速提升的喷射火焰的稳定机制应归因于自燃与活性核在火焰底部的传播之间的竞争。结果，提升的氢射流燃烧的特性沿轴向方向逐渐变化，这在先前的研究中尚未得到充分解决。本文对氢气喷射到空气流中进行了高分辨率的大涡模拟，其重点特别放在湍流结构的演化过程和阻焰机理上。为了分析湍流对化学反应的影响，采用了一种假设的概率密度函数方法来封闭控制方程的源项。数值方案的时间和空间分辨率足够高，可以捕获超音速反应流内部的非定常运动。某些重要物种的预测浓度与通过实验方法测得的浓度非常吻合，证明了数值结果的重要性。从瞬时图像中，大涡模拟再现了由内部射流和热空气流的相互作用所产生的三维流场。根据时间平均分析，燃烧流场可分为三个阶段，即初始混合，自燃和随后的湍流火焰。显然，超音速反应流经过从自燃到部分预混火焰的过渡，并且沿轴向的统计特征相应地发生变化。