高压下湍流和火焰自身不稳定性对预混湍流火焰结构影响规律研究

Premixed turbulent flame structure is not only the key point for understanding turbulence-flame interaction but also the experimental basis for building turbulent combustion model. Experimental study will be conducted on the fundamental continuous premixed turbulent flames. Turbulence is measured and OH-PLIF diagnostic technique is utilized on flame front structure detection, operating with the high-pressure combustion facility, at different pressures within the wide range of turbulence intensity. A self-developed flame front extracting algorithm and image processing software are used to process the OH-PLIF image statistically. Meanwhile, a hybrid Navier-Stokes/Level-set methodology, within the context of the hydrodynamic model, will be used to examine the 2D/3D turbulent Bunsen flames corresponding to experiments. The relationship between the detected 2D flame front and the real 3D spatial structure will be derived theoretically to establish the 3D flame estimation model, which can be validated by the numerical results. Accompany with the numerical results, the role of turbulence perturbation and flame intrinsic instability on 2D/3D flame front structure will be clarified at different pressures and turbulence intensities. The integral scale effect on the flame front under various pressures will be illuminated. This work will reveal the mechanism of action of pressure, turbulence and intrinsic instability on flame front structure. It can also provide experimental data for revealing flame-turbulence interaction mechanism as well as establishing and developing turbulent combustion model, furthermore, provide the scientific guidance for advanced combustor designing and exploitation in the end.

预混湍流火焰结构是理解湍流-火焰相互作用，构建湍流燃烧模型的实验基础。本项目以连续燃烧基础预混湍流火焰为研究对象，结合高压燃烧实验平台和OH-PLIF燃烧诊断技术，获得高压下流场参数，宽广湍流范围的火焰前锋面结构。自主开发前锋面提取算法和图像处理软件对OH-PLIF图片进行统计分析处理，并利用Hybrid NS/Level-set方法结合动力学模型计算相应条件下二维/三维本生灯火焰。理论推导探测的二维前锋面到三维真实火焰结构的关系，建立三维结构估计方法，并利用数值结果进行修正。结合数值模拟阐明在不同燃烧压力和湍流强度下扰动和火焰自身不稳定性对二维/三维前锋面结构的不同作用，阐明不同压力下积分尺度对前锋面结构的影响规律，揭示燃烧压力、湍流流场、火焰自身对前锋面的影响机理。最终为揭示湍流燃烧中湍流涡-火焰相互耦合机理、建立和完善预混湍流燃烧模型提供实验数据，为先进燃烧器设计和开发提供科学依据。

预混湍流火焰结构是理解湍流-火焰相互作用，构建湍流燃烧模型的实验基础。本项目以连续燃烧基础预混湍流火焰为研究对象，结合高压燃烧实验平台和OH-PLIF燃烧诊断技术，获得高压下流场参数，宽广湍流范围的火焰前锋面结构。自主开发前锋面提取算法和图像处理软件对OH-PLIF图片进行统计分析处理，并利用Hybrid NS/Level-set方法结合动力学模型计算相应条件下二维/三维本生灯火焰。理论推导探测的二维前锋面到三维真实火焰结构的关系，建立三维结构估计方法。结合数值模拟阐明在不同燃烧压力和湍流强度下扰动和火焰自身不稳定性对二维/三维前锋面结构的不同作用，阐明不同压力下积分尺度对前锋面结构的影响规律，揭示燃烧压力、湍流流场、火焰自身对前锋面的影响机理。项目首先获得了高压宽广湍流强度范围的火焰图片, 并针对高压火焰以及高湍流强度火焰开发了一套完整的高效、可靠的湍流火焰OH-PLIF图片结果处理方法。通过统计分析火焰结构规律，揭示了影响湍流火焰以及湍流燃烧的主要因素，并阐明了流体动力学不稳定性以及湍流尺度对湍流火焰的影响规律。最后开展了动力学模型模拟湍流火焰，本模型不仅能准确捕捉实验上湍流火焰结构规律，并且可以通过控制变量法揭示流体动力学不稳定性以及湍流强度在湍流燃烧中的影响作用。最终为揭示湍流燃烧中湍流涡-火焰相互耦合机理、建立和完善预混湍流燃烧模型提供实验数据，为先进燃烧器设计和开发提供科学依据。