A Study on Atomization and Combustion under Super-Critical Atmospheric Conditions

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The perpose of this study is to clarify the effect of high atmospheric temperature and pressure like a super-critical condition on the atomization and combustion process of a liquid fuel. First, the spray injected by a diesel nozzle was observed by a laser diffraction technique system and the Sauter mean diameter of the diesel spray on evaporating condition was measured. Next, the characteristics of spray which was formed by a swirl atomizer under high atomospheric conditions were observed by the same method. Last, new type of blue flame combustion system was developed to reduce the soot emission.From these three expremental works, we could obtain the useful results of the effect of high temperature and pressure on the spray combustion phenomena.Results are as follows.(1) With an increasing liquid viscosity, the spray angle decreases and the Sauter mean diameter gradually increases. With further increase of the viscosity, the Sauter mean diameter suddenly increases. There is an upper limit of the viscosity to be atomized as a spray of fine droplets.(2) At a high injection pressure, the effect of viscosity on the Sauter mean diameter still remains but the viscosity has no effect on the spray angle.(3) The angle of the spray formed by a swirl atomizer decreases with increasing the ambient pressure. But if the ambient pressure increases beyond 3.0 MPa, the spray angle decreases.(4) The Sauter mean diameter of evaporating spray takes the maxmum value in the evaporating process.(5) New type of blue flame combustor was developed. The principle of this combustion system were quick mixing process of the spray and combustion air by mean of the impinging the air jet to the fuel spray.