燃气轮机燃烧室中进动涡核与火焰相互作用机理研究

A precessing vortex core (PVC), which is frequently encountered in GT-typical swirl combustors, is the most common coherent vortex structure in swirl combustors. It’s generally believed that a PVC has been generated when the swirl centre can be seen to be precessing around the geometric centre of a flame tube. And there is a large amount of evidence that suggests the PVC structures can have a significant impact on transport processes, flow characteristics, fuel atomization and distribution, flame structures and propagation characteristics, and so on upstream of combustors. Therefore, the PVCs will significantly impact on combustor performance eventually. The focus of this project is on the PVC phenomena and some related key scientific problems in turbulent swirling combustion in gas turbine combustors, on which basic science research will be carried out experimentally, numerically and theoretically. The main research contents in this study are as follows. The rules of distribution and transportation of flow energy and turbulent kinetic energy under effects of PVCs will be revealed. The mechanisms and effects of PVCs on turbulent transports, flame structures and reaction processes will be clarified. At the same time, the effects of heat of combustion and fuel spray parameters on the formation of PVCs and its characteristic parameters will be revealed. Based on the study of the above key scientific problems, an active control method for reaction flow characteristics and combustion processes will be developed by means of controlling characteristic parameters of PVCs. As a result, more efficient combustion can be realized. All the efforts and fruits to be obtained will provide both a theoretical preparation for developing unsteady mechanisms of flame stabilization of swirl combustion and theoretical and technical supports for further improving the performance of high performance gas turbine combustors in the future.

进动涡核（PVC）是旋流燃烧室中经常出现的一种旋流中心围绕火焰筒几何中心轴做周向进动的现象。PVC结构特性对于燃烧室头部输运过程、流场特性、燃油雾化与空间分布、火焰结构与传播特性等将产生十分重要的影响，进而能够对燃烧室性能产生重要影响。本项目针对燃气轮机燃烧室中出现的PVC现象及相关关键科学问题，采用理论分析、数值模拟与实验研究相结合的方法开展基础科学研究。主要研究内容包括：揭示PVC作用下流场动能与湍动能的分配与传递规律；阐明PVC对于湍流输运过程、火焰结构及反应进程的作用机理与影响规律；确定燃烧放热量及燃料喷射参量对于PVC形成及特性参数的影响。通过对于上述重要关键科学问题的研究，获得通过控制PVC特性来对反应流场特性及燃烧过程进行主动控制的规律方法并进而实现高效组织燃烧过程，为建立非稳态旋流燃烧火焰稳定机理提供理论储备，为未来高性能燃气轮机燃烧室性能的进一步提升提供理论和技术支撑。

进动涡核（PVC）是旋流燃烧室中经常出现的一种旋流中心围绕火焰筒几何中心轴做周向进动的现象。PVC结构特性对于燃烧室性能能够产生重要影响。本项目主要研究内容包括：揭示了PVC作用下流场动能与湍动能的分配与传递规律；阐明了PVC对于湍流输运过程、火焰结构及反应进程的作用机理与影响规律；确定了燃烧放热量及燃料喷射参量对于PVC形成及特性参数的影响。研究表明，PVC等大尺度涡结构的能量一般占流场总脉动能量的75%以上；在PVC进动过程中，与回流区之间进行物质与能量的交换，并脱落出进动的小尺度涡群，其能量迅速衰减，最终导致PVC耗散，其中，PVC等大尺度涡主要完成大空间范围能量与组分的输运，小尺度涡主要完成小空间范围能量交换与组分掺混，小尺度涡是燃烧反应发生的主要位置。PVC进动将会带动火焰面运动，火焰面不断被拉伸、扭曲、撕裂和重组，并对扩散火焰和预混火焰的分布和形态产生影响。燃烧放热对PVC结构产生抑制作用，导致其结构体积变小及其强度减弱。燃油喷射位置及流量变化对于PVC的形成及结构影响相对较小。研究中定义了PVC的特性参数，如PVC的轨迹、进动频率、扩张角度、臂间距等，并分析了燃烧室进出口压差、燃烧放热量、旋流器叶片角度等因素对于这些参量的影响规律。上述研究工作及成果为建立非稳态旋流燃烧火焰稳定机理提供理论储备，为未来高性能燃气轮机燃烧室性能的进一步提升提供理论和技术支撑。