柴油机喷雾燃烧特性实验研究
发布时间：2019-07-08 15:31
【摘要】：随着人们对环境保护意识的增强以及国家针对机动车排放相关法律法规的完善,直喷式柴油机较高的颗粒物排放成为限制柴油机发展的重要因素,这也成为许多学者重点研究的课题。最近的研究表明,直喷式柴油机喷雾燃烧时的空气卷吸率对碳烟的形成具有重要影响。而直喷柴油机的火焰浮起长度(Flame Lift-Off Length)以及喷雾锥角等能够通过影响油气混合进而影响到空气卷吸率。本文设计改进了定容燃烧弹系统实验设备以适应对燃油喷雾燃烧特性参数的测量。通过改进后的燃烧弹系统对柴油火焰浮起长度进行测量。并利用温度、压力等传感器测量实时温度、压力等变化值。在此基础上研究了定容燃烧弹内的环境温度、环境密度、环境压力以及喷油压力等参数对火焰浮起长度的影响。对比国内外研究成果,从而估算了空气卷吸率随这些参数的变化规律,进而分析了燃烧参数对碳烟(soot)生成的影响。实验结果发现,在稳态条件下,也就是在体积无变化的燃烧弹内,初始环境的温度、压力以及密度的增加会减小火焰浮起长度,从而降低空气卷吸率,其中火焰浮起长度对实验条件下的环境温度敏感度要大于环境压力,火焰浮起长度相对于环境温度和密度的变化为非线性的;火焰浮起长度随喷射压力的增加而增加。在定性分析了火焰浮起长度的变化趋势的基础上进行了定量分析,利用1stOpt软件的曲线拟合和参数优化功能得到了在稳态条件下柴油喷雾燃烧火焰浮起长度的经验公式。从而得出燃烧室温度、压力以及喷油压力等参数对柴油在喷雾燃烧中的空气卷吸率以及碳烟生成的影响。进而利用煤油作为对比燃油进行了同样的实验分析,得出了其火焰浮起长度大小以及变化趋势并绘制了两种燃油对比分析图。在两者的对比分析图中,将两种燃油浮起长度相同时呈现的曲线称之为等高线现象。通过等高线位置的移动得出两者变化趋势的不同。根据两者烃族组分的不同进行了分析,解释了其合理性并预测了不同含碳原子量的燃油浮起长度变化趋势。本文对火焰浮起长度的研究有助于未来在柴油机研发中,通过改善燃烧室参数改变浮起长度以及空气卷吸率,从而尽可能控制碳烟的生成,进一步降低排放。
[Abstract]:With the improvement of the awareness of environmental protection and the improvement of the national laws and regulations on the emission of motor vehicles, the high particulate emission of the direct injection diesel engine has become an important factor to limit the development of the diesel engine, which has also become the subject of the key research of many scholars. Recent studies have shown that the rate of air entrainment in the spray combustion of a direct injection diesel engine has an important effect on the formation of soot. The flame lift-off length and the spray cone angle of the direct injection diesel engine can affect the air volume suction rate through the influence of oil and gas mixing. In this paper, the experimental equipment of the constant-volume combustion bomb system is designed to adapt to the measurement of the fuel spray combustion characteristic parameters. And measuring the floating length of the diesel flame by the improved combustion bomb system. And the changes of the real-time temperature, the pressure and the like are measured by means of sensors such as temperature, pressure and the like. On this basis, the influence of the parameters such as the ambient temperature, the environmental density, the ambient pressure and the injection pressure on the floating length of the flame was studied. The effect of the combustion parameters on the soot formation is also analyzed by comparing the research results at home and abroad. the experimental results show that the temperature, pressure and density of the initial environment can reduce the flame floating length under the steady-state condition, that is, in the volume-free combustion bomb, so that the air volume suction rate is reduced, The sensitivity of the flame floating length to the ambient temperature under the experimental conditions is higher than the ambient pressure, and the variation of the flame floating length with respect to the ambient temperature and the density is non-linear; the flame floating length is increased with the increase of the injection pressure. On the basis of the qualitative analysis of the variation trend of the flame floating length, the empirical formula of the floating length of the diesel fuel spray combustion flame under the steady-state condition is obtained by using the curve fitting and the parameter optimization function of the 1stOt software. So as to obtain the influence of the parameters of the temperature, the pressure and the injection pressure of the combustion chamber on the air volume absorption rate and the soot formation of the diesel in the spray combustion. In the same way, kerosene is used as the comparative fuel to carry on the same experimental analysis, the length and the variation trend of the flame floating length are obtained, and the two fuel-fuel contrast analysis graphs are drawn. In the comparative analysis of the two, the curves presented when the two fuel float lengths are the same are called contour phenomena. The movement of the contour position results in a difference in the changing trend of the two. Based on the analysis of the different hydrocarbon group components, the rationality and the prediction of the variation trend of the fuel floating length of different carbon-containing atoms are explained. In this paper, the study of the length of the flame is helpful to the future in the development of the diesel engine, and the floating length and the air volume absorption rate can be changed by improving the parameters of the combustion chamber, so as to control the generation of the soot as much as possible and further reduce the emission.
【学位授予单位】：重庆交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TK421.2
本文编号：2511688
[Abstract]:With the improvement of the awareness of environmental protection and the improvement of the national laws and regulations on the emission of motor vehicles, the high particulate emission of the direct injection diesel engine has become an important factor to limit the development of the diesel engine, which has also become the subject of the key research of many scholars. Recent studies have shown that the rate of air entrainment in the spray combustion of a direct injection diesel engine has an important effect on the formation of soot. The flame lift-off length and the spray cone angle of the direct injection diesel engine can affect the air volume suction rate through the influence of oil and gas mixing. In this paper, the experimental equipment of the constant-volume combustion bomb system is designed to adapt to the measurement of the fuel spray combustion characteristic parameters. And measuring the floating length of the diesel flame by the improved combustion bomb system. And the changes of the real-time temperature, the pressure and the like are measured by means of sensors such as temperature, pressure and the like. On this basis, the influence of the parameters such as the ambient temperature, the environmental density, the ambient pressure and the injection pressure on the floating length of the flame was studied. The effect of the combustion parameters on the soot formation is also analyzed by comparing the research results at home and abroad. the experimental results show that the temperature, pressure and density of the initial environment can reduce the flame floating length under the steady-state condition, that is, in the volume-free combustion bomb, so that the air volume suction rate is reduced, The sensitivity of the flame floating length to the ambient temperature under the experimental conditions is higher than the ambient pressure, and the variation of the flame floating length with respect to the ambient temperature and the density is non-linear; the flame floating length is increased with the increase of the injection pressure. On the basis of the qualitative analysis of the variation trend of the flame floating length, the empirical formula of the floating length of the diesel fuel spray combustion flame under the steady-state condition is obtained by using the curve fitting and the parameter optimization function of the 1stOt software. So as to obtain the influence of the parameters of the temperature, the pressure and the injection pressure of the combustion chamber on the air volume absorption rate and the soot formation of the diesel in the spray combustion. In the same way, kerosene is used as the comparative fuel to carry on the same experimental analysis, the length and the variation trend of the flame floating length are obtained, and the two fuel-fuel contrast analysis graphs are drawn. In the comparative analysis of the two, the curves presented when the two fuel float lengths are the same are called contour phenomena. The movement of the contour position results in a difference in the changing trend of the two. Based on the analysis of the different hydrocarbon group components, the rationality and the prediction of the variation trend of the fuel floating length of different carbon-containing atoms are explained. In this paper, the study of the length of the flame is helpful to the future in the development of the diesel engine, and the floating length and the air volume absorption rate can be changed by improving the parameters of the combustion chamber, so as to control the generation of the soot as much as possible and further reduce the emission.
【学位授予单位】：重庆交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TK421.2
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