Elucidation and Modeling of Turbulent Premixed Combustion Phenomena in a High-Pressure and High-Temperature Environment

本研究旨在探索高压高温下的湍流燃烧现象。研究了高压室中稳定的预热混合物的湍流预混火焰。对火焰进行了精确观测，并测量了湍流燃烧速度和由达里厄-朗道流体动力不稳定性引起的火焰起皱的最小尺度。考察了压力和预热的影响，建立了高压高温下的湍流燃烧模型。研制了空气电加热器，并在高压室内安装。由于高温密封的限制，最大压力和温度分别为1.0 MPa和573 K。实验中使用了甲烷/空气混合物。分析了OH-PLIF图像的分形内截止作为火焰起皱的最小尺度，明确了最小起皱尺度与大湍流雷诺数下573 K时的达里厄-朗道流体动力不稳定性特征尺度之间的显著相关性。通过对湍流能谱的精确测量，证实了高压高温下流动湍流无量纲能谱的Kolmogorov相似定律，并且可以认为一个相当于平均涡管直径的特征尺度是初始流动扰动最大波数所对应的尺度，该尺度比Kolmogorov尺度大10倍左右。当湍流尺度小于不稳定尺度时，由于达里-朗道流体动力不稳定性的影响，最小起皱尺度保持不变。采用本研究开发的PIV和OH-PLIF方法同时测量高压和高温层流燃烧速度。首先进行了H2/O2/He混合物的化学计量实验，然后进行了甲烷/空气混合物的化学计量实验。对反应机理进行了改进。利用数值和实验数据对紊流燃烧进行了分析。最后，基于OH-PLIF图像处理进行了湍流燃烧速度测量，建立了基于湍流雷诺数的高压高温湍流燃烧速度估算模型。少

This research aimed to explore turbulent combustion phenomena at high pressure and high temperature. Turbulent premixed flames for preheated mixture stabilized in a high-pressure chamber were investigated. Precise observations of the flame and measurement of turbulent burning velocity and the smallest scales of flame wrinkling due to Darrieus-Landau hydrodynamic instability were performed. Effects of pressure and preheating were examined and the turbulent combustion model at high pressure and high temperature was developed.Electrical heater of the air was developed and installed in the high-pressure chamber for the present experiment. The maximum pressure and temperature were 1.0 MPa and 573 K because of the limitation of high-temperature seals. Methane/air mixtures were used for the experiments. The fractal inner cutoff of OH-PLIF images as the smallest scale of flame wrinkles was analyzed, and it was clarified that the significant correlation between the smallest wrinkling scale and … More characteristic scale of Darrieus-Landau hydrodynamic instability even at 573 K for large turbulence Reynolds number. Precise measurement of the energy spectrum of turbulence showed that Kolmogorov's similarity law for nondimensional energy spectrums of flow turbulence at high pressure and high temperature was confirmed, and a characteristic scale equivalent to the average vortex-tube diameter, which is about 10 times larger than the Kolmogorov scale can be considered as a scale corresponding to the largest wavenumber of initial flow disturbances. It was also shown that the smallest wrinkling scale becomes constant when this turbulence scale becomes smaller than the instability scale because of the effect of the Darrieus-Landau hydrodynamic instability. Measurements of laminar burning velocity at high-pressure and high-temperature were performed using simultaneous PIV and OH-PLIF methods developed in this research. Experiments for stoichiometric H2/O2/He mixture were performed first and then methane/air mixture was examined. Modification of the reaction mechanism was also performed. The numerical and experimental data were used for the analysis of the turbulent combustion.Finally, measurements of turbulent burning velocity based on image processing of OH-PLIF images were conducted and the model to estimate turbulent burning velocity at high-pressure and high-temperature based on turbulent Reynolds number was developed. Less