高速燃气与空气在隔板后相遇形成的混合层流动模型在高超声速飞行器动力系统中广泛存在，已有的针对超声速混合层流动过程和机理的高精度数值模拟研究多忽略隔板，针对超声速带隔板混合层的直接数值模拟工作十分有限。以来流对流马赫数为0.8、隔板厚度为4 mm的三维超声速带隔板混合层为研究对象，采用自主开发的高精度直接数值模拟程序，系统开展了流场精细结构演化和湍流统计特性研究。研究结果表明，两股超声速来流在隔板尾缘形成回流区后汇合成超声速混合层，经过很短距离便开始转捩，最后进入自相似区域。在转捩区域发现了各种典型涡结构，其中由Λ涡发展形成的发卡涡结构主导了转捩区流场的演化。在转捩后期，发卡涡脱落、缠绕形成了多重链状涡结构。在自相似区域，流向涡结构主导着流场，且大量小尺度涡结构充斥其中。与无隔板混合层流动不同，隔板显著促进了流动转捩且带来了强烈的三维特性，在展向不同位置处，流场结构演化速度有显著差异，同时涡结构在展向方向相互作用更加剧烈。湍流统计分析表明，带隔板混合层转捩阶段雷诺剪切应力呈单峰分布；自相似区域雷诺切应力项与实验结果相符，其中，横向雷诺应力项较无隔板研究结果显著增长，这说明隔板的出现给流场带来了较大的横向扰动；在混合层中心区域，平坦因子接近3，说明自相似区域已达到各向同性状态。获得的超声速带隔板混合层的三维涡结构演化、混合层生长过程量化表征、流场湍流统计结果，可为相关的实验和数值模拟研究提供数据参考。

The mixing layer flow model can be easily found in super-sonic combustion ramjet propulsion systems when high-speed fuel gas and air encounter. Most high-precision direct numerical simulation on the flow evolution and mechanism of mixing layer are based on the flow model without splitter plate， and few research consider the effect of splitter plate on the mixing layer. Therefore， the three-dimensional supersonic mixing flow model with a splitter plate is taken as the research subject， where the inflow convective Mach number is 0.8 and the thickness of splitter plate is selected as 4 mm. Using the self-developed high-precision direct numerical simulation program， both the evolution of fine flow structure and the turbulence statistics in supersonic mixing flow down-stream the spitter plate are systematically analyzed. The research results show that after the two supersonic incoming flows form a recirculation zone at the trailing edge of the partition， they merge into a supersonic mixing layer. Transition begins after a very short distance and finally the flow reaches the self-similar stage. Various typical vortex structures generate in the flow transition region. It is found that the hairpin vortex structures developed from Λ vortices are the primary vortex structures in the transition development region， and in the late stage of the flow transition， the hairpin vortices begin to shed and twist and finally form the multiple necklace-like vortex. In the self-similar region， slender quasi-streamwise vortices exists in this region， and there are numerous small-scale vortex structures scattered in the flow field. Unlike the case without splitter plate， the mixing flow influenced by the splitter plate transits faster and show intense three-dimensional characteristics. At different spanwise locations， there are notable differences in the evolution speed of the flow field structure. Meanwhile， the vortex structures interact more vigorously in the spanwise direction. Through turbulence statistics analysis， it is found that in the transition region of mixing layer with an splitter plate， the Reynolds shear stress follows a unimodal distribution. Besides， the numerical results of the Reynolds shear stress terms in the self-similar region are consistent with the experimental results， notably， the transverse Reynolds stress term increase significantly， indicating that the presence of the splitter plate introduces considerable lateral disturbances to the flow field. Meanwhile， the flatness factor value approaches 3， indicating that the self-similar region has achieved an isotropic state. The three-dimensional vortex structure evolution， quantitative characterization of the mixing layer growth process， and turbulence statistics results of the supersonic mixing layer with the splitter plate obtained can provide data references for related experimental and numerical simulation studies.