Research and Development of High-Intensity Hydrogen Combustor for Gas Turbine

氢燃料燃烧时不会产生温室效应的二氧化碳，因此作为下一代燃料具有很大的吸引力。本研究的目的是开发一种以氢为主要燃料的微型燃气轮机燃烧室。层流火焰的火焰拉伸熄灭是氢-空气预混火焰的一个基本特征。因此，我们首先测量了层流氢-空气预混火焰的消光特性。结果表明，氢-空气预混火焰对火焰拉伸的耐受性比典型的碳氢燃料高一到两个数量级。然后研究了湍流对湍流预混火焰消光的影响，发现具有Kolmogorov微尺度的涡流在湍流氢-空气预混火焰消光中起重要作用。氢气-空气预混火焰的燃烧速度非常快，很容易引起更多的回火。因此，我们将扩散燃烧应用于微型燃气轮机燃烧室。研究发现，在化学反应开始前，冲击射流通过强湍流显著促进了湍流混合，即使燃料和空气分开供应，也会发生预混合燃烧。利用冲击射流，设计了在大降压比下无涡流稳定运行的高强度模型燃烧室。通过使用该燃烧室，发现撞击射流引起的湍流特性受空气与燃料动量比的控制。在燃料动量较大的情况下，产生了分布反应区，燃烧强度极高。将碰撞射流的概念应用于微型燃气轮机模型燃烧室。为了减少热损失，提高燃烧稳定性，在燃烧室中引入了陶瓷衬垫。因此，稳定区间被扩大。燃烧室中稳定化学物质浓度均匀，废气中NOx浓度极低。因此，空气和燃料的碰撞射流可以应用于微型燃气轮机的燃烧室。少

Since hydrogen fuel, when it is burned, produces no carbon dioxide which has the greenhouse effects, it is attractive as the fuel of the next generation. The objective of the present study is the development of a combustor for a micro gas turbine in which hydrogen is used as a main fuel. The extinction of laminar flame by flame stretch is a fundamental feature of the hydrogen-air premixed flame. Therefore, at first, we measured the extinction characteristics of the laminar hydrogen-air premixed flames. It was made clear that the hydrogen-air premixed flame has one or two order of magnitude higher tolerance to the flame stretch than the typical hydrocarbon fuels. Then the effect of turbulence on the extinction of the turbulent premixed flame was studied and eddies with the Kolmogorov micro scale were found to play an important role in the extinction of the turbulent hydrogen-air premixed flame. The burning velocity of a hydrogen-air premixed flame is extremely fast and it easily causes … More flash back. Therefore, we apply the diffusion combustion in the combustor of a micro gas turbine. It was found that the impinging jets promote significantly the turbulent mixing by strong turbulence before the chemical reaction begins and that the premixed combustion occurs even though fuel and air are supplied separately. Applying the impinging jets, we designed high-intensity model combustor which operates stably within wide turn-down ratios without swirl. By using this combustor, characteristics of turbulence induced by the impinging jets was found to be controlled by the momentum ratio of air to fuel. For the case of large momentum of fuel, the distributed reaction zone was produced and the combustion intensity was extremely high. The concept of the impinging jets was applied to the model combustor of a micro gas turbine. To reduce the heat loss and to increase the combustion stability, a ceramic liner was introduced in the combustor. As a result, the stability range was widened. The concentration of stable chemical species was uniform in the combustion chamber and NOx concentration in the exhausted gas was found to be extremely low. Therefore, the impinging jets of air and fuel can be applied to the combustor of a micro gas turbine. Less