不同初始温度和水蒸气稀释比对乙醇/异辛烷层流火焰特性的影响

在101.3kPa的初始条件下,利用定容燃烧弹系统结合高速纹影摄像技术,研究不同水蒸气稀释比(0～10%)和不同初始温度(400～500K)下乙醇体积分数为10%的乙醇/异辛烷混合燃料(E10)的层流火焰特性。试验结果表明:E10/空气的层流火焰速度随着水蒸气稀释比的增加呈线性下降,随着初始温度的升高呈指数增加;无量纲层流火焰速度随着水蒸气稀释比的增加而下降,受当量比的影响不大。化学敏感性分析表明:链分支反应有利于提高E10/空气层流火焰速度,链终端反应则会降低层流火焰速度。水蒸气的稀释作用、热力学作用、直接反应作用和三体作用都会降低E10层流火焰速度,其中稀释作用的影响最大。

Effects of initial Temperature and Water Vapor Concentra-tion on Laminar Flame Characteristics of Ethanol/Isooctane Mixture

The laminar flame characteristics of ethanol/isooctane mixture with 10% ethanol volume fraction (E10) were investigated using a constant volume combustion bomb system and high-speed schlieren visualization technology at different water vapor concentrations (0-10%) and initial temperatures (400-500 K). The experimental results showed that the laminar flame speeds of E10/air decreases linearly with the in-crease of water vapor dilution ratio, and it increases exponentially with the increase of initial temperature. The dimensionless laminar flame speed decreases as the water vapor dilution ratio increases, and the effect of equivalence ratio is not significant. The sensitivity analysis showed that the chain branch reactions are beneficial to increase the laminar flame speed of E10/air, but the chain terminal reactions reduce the laminar flame speed. The dilution effect, thermal effect, direct reaction effect and three-body effect of water vapor are the reasons that make the reduction of the laminar flame speed of E10/air, and the dilution effect plays a leading role.