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

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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