A Study of Turbulent Combustion Mechanism in a High-Pressure, High-temperature and High Water-vapor Environment

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The purpose of this project is to explore turbulent combustion mechanism for low oxygen mixture highly diluted with water vapor considering the applications of exhaust gas recycling to high-load combustion at high pressure. Because the exhaust gas consists of water vapor, carbon dioxide and nitrogen, the effects of dilution especially with water vapor and carbon dioxide on combustion characteristics were investigated systematically. For turbulent and laminar premixed flames from ordinary pressure to high pressure, flame structure and burning velocity were measured using laser diagnostic methods.In the first year, parallel to the experiments on carbon dioxide dilution effects on high-pressure turbulent premixed flames, an apparatus to generate water vapor in a high-pressure environment using a copper cylinder, rod heaters and steel wool connected to a water mass-flow controller was developed and it was confirmed that the apparatus stably provided water vapor over a wide range of water s … More upply. Using the apparatus, differences in light emission from the flames depending on the dryness of the mixture were confirmed.In the second year, experiments for turbulent premixed flames diluted with water vapor up to 0.1 of moler fraction were successfully performed at high pressure and high temperature. By using OH-PLIF, profiles of the mean progress variable based on 500 OH-PLIF images were analyzed and the turbulent burning velocity and mean volume of the turbulent flame region were measured, and then compared with those for carbon dioxide dilution. Moreover, simultaneous measurement of OH-PLIF and PTV was performed for laminar flames to measure the laminar burning velocity and the effects of water vapor. As a result, it was found that the burning velocity for the mixtures diluted with water vapor was larger than that of numerical simulation in the fuel rich region and it was implied that fuel reforming reactions causes the phenomenon. Also, it was found that concentration of carbon monoxide in the burnt gas was reduced as an effect of the water vapor addition. Less