面向航空燃气涡轮的受限空间超紧凑燃烧的基础机理研究

In continuing the effort to push the limitations of traditional gas turbine engines, Ultra Compact Combustors offer unique solutions to minimize engine size and weight. They accomplish this by reducing the number of components in the engine core and perform the combustion in a circumferential cavity that encircles the core flow. Within this cavity, the fuel is injected rich. Burning continues to occur in the vane passage beneath the circumferential cavity which must be completed in a controlled manner prior to the inlet plane of the turbine rotor. Furthermore, the temperature distribution at the exit of the vane passage must be controlled to generate high work extraction from the turbine. This research shall vary the cavity equivalence ratio, g-loading, bulk flow rate, and mass flow ratio with the core flow to characterize the impact of each of these parameters on the exit conditions. The primary metrics for comparison are the exit temperature and pressure profiles, the emissions characteristics, and the overall system losses. Overall, the goal of this research effort is to establish a set of criteria that produced an exit flow condition similar to that created by a traditional axial combustion system, thus realizing the weight savings offered by the Ultra Compact design. Results will show the shapes and magnitudes of the exit temperature and pressure profiles, quantify the emissions species across the exit plane, and establish a benchmark for the overall system losses as a function of the cavity parameters.

应对常规航空燃气涡轮发动机在尺度、油耗、机动性和推重比等性能的改善与提高，亟待在组织燃烧新方法上有所突破，小空间超紧凑燃烧方案成为未来发展的方向之一，但航发在飞行包线下给燃烧组织带来的是高加速与高温升、高重力与微重力的交替、交变、突变环境下的燃料雾化、蒸发、扩散，对燃烧的稳定性和控制性均提了严峻的挑战，本项目基于前期开展的二种新构式小空间超紧凑组织燃烧机制的研究基础积累，开展小空间超紧凑燃烧的应用基础机理研究，系统研究超紧凑小空间内旋流、涡流、反应流交互的湍流燃烧微观机理特性，通过流动与燃烧耦合机理和控制机制，探索和支撑应用技术亟需的底层基础机理。本项目的关键机理研究包括：受限小空间内离心力对稳焰特性影响，紊流漩涡扰动对燃烧结构稳定性影响，二次气流不均匀扰动对火焰速度分布的影响，小空间超重力与微重力交变对湍流燃烧压力梯度形成的涡流大小的影响，火焰稳定性与结构特征参数耦合机制等基础机理。

设计了主次流轴向进气型超紧凑燃烧室，从而实现了二次的流轴向进气，这一设计具有极大的实际应用潜力。研究了燃烧环宽度及燃烧环形式对燃烧性能的影响，设计并计算了不同后倾燃烧环形式下燃烧室的总体性能。分析了二次流进气方向对超重力环境及燃烧性能的影响，研究了射流盘轴向角度对超重力场的形成及射流盘上扬角度对燃料滞留时间的影响，并设计和优化了节流盘以获得预期的主次流分流比和较小的压力损失。设计了并优化了环前-环顶、环前-环后进气对燃烧组织的影响，从而使燃烧环的高温区前移降低壁面热负荷，改善燃烧室出口温度分布。进行了超重力燃烧的机理研究，研究中发现的瑞利泰勒不稳定性现象可以进一步指导超紧凑燃烧室的设计。得出结论是超紧凑燃烧室具有提高传统涡轮发动机总体性能的潜在优势，是未来航空发动机高效增推的可实现性技术方向，对涡轮燃气轮机的发展具有重大意义。