论文标题
精细乙醇喷雾剂中的火花点燃的内核动力及其与最低点火能量的关系
Spark-ignited kernel dynamics in fine ethanol sprays and their relations with minimum ignition energy
论文作者
论文摘要
用欧拉 - 欧拉群法和详细的化学机制研究了乙醇液滴/蒸气/空气混合物的火花点火。用蒸发完成前（ECF）量化火焰内核 - 滴滴的相互作用。因此，可以根据ECF和火焰前部之间的相对位置，即同质和异质喷雾火焰来定义两类的喷雾火焰。引入了火焰前部（简称火焰ER）的基于元素的当量比（ER），以测量蒸发喷雾剂中的气体组成。对于整体燃油混合物，准平台球形火焰（QSSF）是由于瘦火焰ER而发生的，而QSSF前沿的成分是同质的。对于整体富含燃料的两相混合物，当液滴直径为15μm的燃油喷雾剂的液滴直径为15μm时，可以观察到燃油叶和燃料富含燃料富含燃料的背景气体时的重新点燃。这是由于浓烈的火焰ER和/或强烈的蒸发热损失。同时，内核出生在异质的混合物中，并过渡到均匀状态。对于整体瘦和丰富的两相混合物，燃油液滴都会影响可景性和火焰轨迹。此外，点火能量会影响内核开发早期的火焰ER和前距离。最后，研究了具有不同气体和总体ER的最低点火能（MIE）。
Spark ignition of ethanol droplet/vapor/air mixture is studied with a Eulerian-Eulerian method and detailed chemical mechanism. The flame kernel-droplet interaction is quantified with an evaporation completion front (ECF). Two categories of spray flames can hence be defined based on the relative location between the ECF and flame front, i.e., homogeneous and heterogeneous spray flames. An element-based equivalence ratio (ER) at the flame front (flame ER for short) is introduced to measure the gas composition in evaporating sprays. For overall fuel-lean mixtures, quasi-stationary spherical flame (QSSF) occurs due to lean flame ER and the composition at the QSSF front is homogeneous. For overall fuel-rich two-phase mixtures, re-ignition, after the spark-ignited kernel fails, is observed when the droplet diameter is 15 μm for fuel sprays with both fuel-lean and fuel-rich background gas. This is due to rich flame ER and/or strong evaporative heat loss. Meanwhile, the kernel is born in a heterogeneous mixture and transition into homogeneous state is found. For both overall lean and rich two-phase mixtures, fuel droplets affect the ignitability and flame trajectories. Moreover, ignition energy affects the flame ER and front distance at the early stage of kernel development. Lastly, the minimum ignition energies (MIE) with different gas and overall ERs are investigated.
