Instability of Premixed Flame and its Turbulent Combustion Properties under High Pressure

在这项研究中，压力对预混火焰传播的影响进行了研究。去年的研究表明，Markstein长度可以很好地反映火焰拉伸对层流燃烧速度的影响，并且Markstein长度随压力的变化而变化，今年的研究发现，Markstein长度较小时，火焰不稳定性显著。当混合物的马克斯坦长度较小时，球形层流火焰表面会产生裂纹。对于贫甲烷和富丙烷混合物，Markstein长度随压力的增加而减小。随着压力的增加，裂纹在扩展的早期阶段形成。对于Markstein长度较小的混合物，火焰被细胞覆盖。随着Markstein长度的减小，从层流火焰向胞状火焰转变的时间变得更早。随着压力的增加和Markstein长度的减小，胞体尺寸也变小.

In this study, the effects of pressure on the premixed flame propagation was investigated. In the last year, we had shown that the effects of flame stretch on the laminar burning velocity could be evaluated well by the Markstein Length and it varied according to the pressure.In this year, our study found that the flame instability was notable when the Markstein Length was small. When the Markstein Length of the mixture was small, some cracks were formed on the surface of the spherical laminar flame. Lean methane and rich propane mixtures showed this properties.For all the mixtures examined in this study, Markstein Length became small according to the pressure. Cracks were formed in the early stage of the propagation with increasing the pressure. For some mixture with small Markstein Length, flame was covered with cells. The timing of this transition to cellular flame from laminar flame became earlier as the Markstein Length was smaller. The size of cell also became small with increasing the pressure and decreasing the Markstein Length.