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，湍流预混火焰的层次结构进行了研究，发展有效的控制方案，在许多工程应用，如燃气轮机湍流燃烧。考虑到详细的或简化的动力学机理以及热特性和输运特性的温度依赖性，对氢气/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）。从高雷诺数湍流预混火焰的DNS出发，阐明了湍流惯性子区火焰锋面的层次结构，并基于火焰锋面的层次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。高强度湍流预混火焰的DNS显示了局部火焰元素的层次结构。对甲烷/空气湍流预混火焰进行了三维数值模拟， ...更多信息 首次揭示了湍流预混火焰的局部熄灭机理。为了实验研究湍流预混火焰的分层结构，人们开发了高空间分辨率、时间分辨的激光诊断技术，例如双平面时间分辨立体粒子图像测速、同时进行的CH-OH PLIF和立体粒子图像测速测量以及CH双脉冲PLIF。双平面时间分辨立体PIV给出了湍流截面上的所有速度和速度梯度分量，最高可达26.7 kHz。同时CH-OH PLIF和立体PIV测量导致实验和DNS之间的直接比较。CH双脉冲PLIF可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点。为了开发有效的湍流燃烧控制方案，采用激光诊断技术研究了噪声控制旋流稳定湍流燃烧室的火焰结构，从声源角度阐明了燃烧噪声与三维火焰结构的关系。为了实现湍流燃烧场的主动控制，研制了一种半导体激光吸收式传感器，并在噪声控制旋流稳定湍流燃烧室中对其性能进行了研究。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