Developments of High-Efficiency and Low-Emission Gas Turbine Combustors by Diode-laser Absorption Measurements

为了研制高效、低排放的燃气轮机燃烧室，研究了二极管激光吸收测量和燃烧噪声、燃烧振荡、CO_2和NO_x排放的有效控制因素。对氢/空气和碳氢/空气湍流预混火焰进行了直接数值模拟，考虑了详细的动力学机制和传递和热性质的温度依赖性。利用直接数值模拟的结果，对二极管激光吸收测量进行了模拟，并阐明了测量结果的准确性。结果表明，应用于燃烧气体的二极管激光吸收测量具有足够的精度。在数值模拟的基础上，研制了基于二极管激光吸收的H_2O和CO_2吸收测量系统。测量在基本实验室燃烧器中进行，以验证诸如物种浓度，温度和时间分辨率的准确性。通过本文的研究，指出了二极管激光吸收测量的优点和局限性。从直接数值模拟的结果出发，研究了NO_x生成速率与局部热释放速率、火焰前缘曲率和应变速率等局部火焰结构之间的关系，提出了有效的排放控制方案。结果表明，CH浓度是NO_x的一个很好的控制因子，因为局部NO_x生成速率与局部放热和CH浓度有很好的相关性。为了确定燃烧噪声和燃烧振荡的有效控制因素，还对化学反应湍流中的声音进行了直接数值模拟。在此基础上，研究了紊流燃烧产生声音的机理，提出了远场声音的预测方法。

In this study, diode laser absorption measurements and effective control factors of combustion noise, combustion oscillations and emissions of CO_2 and NO_x are investigated to develop high-efficiency and low emission gas turbine combustors. Direct numerical simulations of hydrogen/air and hydro-carbon/air turbulent premixed flames are conducted by taking into account detailed kinetic mechanisms and temperature dependence of transport and thermal properties. By using the results of direct numerical simulation, simulations of diode laser absorption measurements are conducted and the accuracy of those is clarified. It is shown that accuracy of diode laser absorption measurements is enough if it was applied in the burnt gas. Based on the numerical simulations, measurement systems based on the diode laser absorption are developed for H_2O and CO_2 absorption. Measurements are conducted in fundamental laboratory buners to verify accuracy such as species concentration, temperature and time resolutions. From this study, advantages and limitations of the diode laser absorption measurement are shown. From the results of direct numerical simulations, relations between NO_x production rate and local flame structure such as local heat release rate, curvature of the flame front and strain rate are also investigated to develop the effective control scheme of emission. It is shown that CH concentration will be a good control factor of NO_x because the local NO_x production rate is well correlated with the local heat release and CH concentration. To identify the effective control factors of combustion noise and combustion oscillations, direct numerical simulations of sound in chemically reacting turbulence are also conducted. From the results of DNS, sound generation mechanism form turbulent combustion is investigated and prediction method of far field sound is developed.