Investigation of Hierarchical Structure of Turbulent Premixed Flames by High Spatial Resolution Time-Resolved Laser Diagnostics and GRID DNS

在这项研究中，紊流预混火焰的分层结构已经被研究，以开发有效的控制方案紊流燃烧观察到许多工程应用，如燃气轮机。对氢/空气和甲烷/空气湍流预混火焰进行了三维直接数值模拟（DNS），考虑了详细或简化的动力学机制以及热学和输运性质的温度依赖性。从高雷诺数湍流预混火焰的DNS出发，阐明了湍流惯性子范围内火焰锋面的层次化结构，并基于火焰锋面层次化结构和湍流特征长度的尺度分离，提出了一种新的亚网格尺度湍流燃烧模型。此外，高强度湍流预混火焰的DNS还显示了局部火焰元的层次结构。甲烷/空气紊流预混火焰的三维DNS，揭示了紊流预混火焰的局部消光机理，是目前国际上首次对紊流预混火焰进行的三维DNS。为了实验研究湍流预混火焰的分层结构，开发了高空间分辨率、高时间分辨率的激光诊断技术，如双平面时间分辨立体PIV、CH- oh PLIF和立体PIV同时测量以及CH双脉冲PLIF。双平面时间分辨立体PIV给出了湍流横截面上的所有速度和速度梯度分量，最高可达26.7 kHz。同时进行CH-OH PLIF和立体PIV测量，可以直接将实验结果与DNS进行比较。CH双脉冲PLIF允许直接测量局部火焰元件的位移速度。将这些激光诊断结果与DNS的结果进行了比较，并讨论了湍流中火焰结构的特征。为了制定有效的紊流燃烧控制方案，采用激光诊断方法研究了噪声控制的旋流稳定紊流燃烧室的火焰结构，从声源的角度阐明了燃烧噪声与三维火焰结构的关系。为了对湍流燃烧场进行主动控制，研制了一种二极管激光吸收传感器，并在噪声控制的涡流稳定燃烧室中对传感器的性能进行了研究。少

In this study, hierarchical structure of turbulent premixed flames have been investigated to develop effective control schemes for turbulent combustion observed in many engineering applications such as gas turbines. Three-dimensional direct numerical simulations (DNS) of hydrogen/air and methane/air turbulent premixed flames were conducted by taking into account a detailed or reduced kinetic mechanism and temperature dependence of thermal and transport properties. From DNS of high Reynolds number turbulent premixed flame, hierarchical structure of flame front in inertial subrange of turbulence was clarified, and a new subgrid-scale turbulent combustion model was proposed based on the hierarchical structure of the flame front and the scale separation of turbulence characteristic lengths. Furthermore, hierarchical structure in the local flame element is shown by DNS of high-intensity turbulent premixed flames. Three-dimensional DNS of methane/air turbulent premixed flame, which is the fi … More rst DNS in the world, revealed local extinction mechanism of turbulent premixed flame. To investigate the hierarchical structure of turbulent premixed flame experimentally, high spatial resolution, time-resolved laser diagnostics such as dual-plane time-resolved stereoscopic PIV, simultaneous CH-OH PLIF and stereoscopic PIV measurement and CH double-pulsed PLIF have been developed. The dual-plane time-resolved stereoscopic PIV gives all of velocity and velocity-gradients components on a cross section in turbulence up to 26.7 kHz. The simultaneous CH-OH PLIF and stereoscopic PIV measurement leads to the direct comparison between experiments and DNS. The CH double-pulsed PLIF allows a direct measurement for displacement speed of local flame element. The results of these laser diagnostics were compared with those of DNS and the characteristics of flame structure in turbulence were discussed. To develop effective control schemes of turbulent combustion, flame structure of a noise-controlled swirl-stabilized turbulent combustor has been investigate by the laser diagnostics, and the relation between combustion noise and three-dimensional flame structure has been clarified in a view point of the acoustic sound source. For active controls of turbulent combustion field, a diode-laser absorption sensor was developed and the performance of the sensor was investigated in the noise-controlled swirl-stabilized turbulent combustor. Less