宽压力范围受限复杂流动条件下的湍流火焰结构研究

Based on the complex flow conditions and the development trend of the high-pressure, high-temperature and low-emission combustion for the combustors of gas turbine engines, a combustor of optical permeability coupled with strong swirling flow and high-speed parallel and cross jets is proposed for the fundamental study of high-pressure turbulent combustion. By adjusting the flow distribution of swirling, parallel and cross jets, the simple flame or the complex turbulent flame of the radial staging, the axial staging, and the high-speed jet mixing can be implemented. First, the experimental study on the cold flow fields and the turbulent flame structures in the combustor with pressure up to 1.0 MPa is conducted, for the development and validation of the turbulence-combustion model and the real mathematical model of the combustor. Then, the CFD simulation is performed to study systematically the effects of pressure, swirl intensity, jet velocity, and equivalence ratio on the turbulent mixing and the flame structure in the combustor with pressure up to 4.0 MPa. The influence mechanism of the turbulence-chemistry interaction is analyzed, the pressure normalization guideline for the turbulent flame structure is summarized, and the link between low-pressure and high-pressure combustion is established. This project is expected to better understanding of the complex turbulence-combustion interaction within the confined space, and the accumulation of advanced measurement technology for the high-pressure turbulent combustion, providing theoretical support for the technology development of advanced engine combustors.

针对燃气涡轮发动机燃烧室的复杂流动条件以及高压、高温升低污染燃烧的发展趋势，抽象出强旋流、高速平行射流、交叉射流耦合的具有光学通透性的燃烧室进行高压湍流燃烧基础研究。通过调节旋流、平行射流、交叉射流的流量分配，既可以实现简单火焰，又可以实现径向、轴向分级、高速射流掺混等复杂湍流火焰。首先在1.0 MPa压力范围内，实验研究燃烧室的冷态流场和湍流火焰结构，用于发展和验证湍流燃烧模型及燃烧室真实数理模型。然后在4.0 MPa压力范围内，采用计算流体力学模拟系统地研究压力、旋流强度、射流速度、当量比等对燃烧室湍流掺混特性和火焰结构的影响规律，分析提炼湍流与化学反应相互作用影响机理，总结湍流火焰结构的压力模化准则，建立低压与高压燃烧之间的联系。本项目有望深入理解受限空间内复杂湍流和燃烧的相互作用机理，并积累高压湍流燃烧的先进测量技术，为先进发动机燃烧室技术研发提供理论支撑。

燃烧室发展趋势为高压、高温升、低污染燃烧，其流场结构具有强旋流、高速射流、强烈回流等特征，有必要开展高压和复杂流动条件下的湍流火焰结构研究。本项目主要研究了旋流扩散燃烧器、旋流预混燃烧器、模型燃烧室在不同压力条件下的湍流火焰结构，以及旋流、平行射流、交叉射流耦合的燃烧室和轴向分级燃烧室的燃烧特性，压力对湍流火焰结构的影响机理及模化准则。获得了加压的旋流扩散燃烧实验数据，对湍流燃烧模型在加压条件下进行了验证。获得了宽压力范围内三种燃烧室燃烧及排放特性的模拟计算数据，发现三种火焰结构随压力的变化具有相似的规律。在轴向分级和交叉射流条件下的火焰结构具有不同于简单火焰的优良特征，能够降低高当量比燃烧的污染物排放，具有良好的应用前景。从多种模拟数据总结出火焰结构压力模化需要满足流动和热力学两个准则条件，其中流动临界条件为出口雷诺数高于100000，而热力学条件为压力高于0.5 MPa，这对燃烧室的设计和试验具有重要的参考价值。