Abstract The present study addresses the autoignition and detonation characteristics of n-heptane/air mixture with water droplets in a confined one-dimensional reactor. A Eulerian-Eulerian formulation for gas and liquid phases is employed to simulate multi-component, fully compressible and reactive multi-phase flows. The parametric investigations covering a range of droplet diameters and number densities are conducted to understand the reaction front development in gas phase and droplet evaporation characteristics under different gaseous combustion conditions. Four modes of autoignition behaviours in the reactor are identified and they are found to greatly depend on both droplet diameter and number density. At a relatively small droplet diameter and/or number density, detonation is initiated by hot spot but no autoignition occurs at the right boundary. When both or either of them increase, autoignition occurs at the right boundary and the reaction front may further evolve into detonative or deflagrative waves. This is because the temperature inhomogeneity in that region is considerably enhanced. Furthermore, droplet diameter and number density are used to quantify the different modes of autoignition and detonation development. For the droplet evaporation dynamics during the reactive front development process, various mechanisms are observed, related to the different effects dominated by the velocity difference between two phases (characterized by the droplet Reynolds number), high local gas pressure and also the droplet temperature. This results in non-monotonic spatial distributions of droplet evaporation rate in the reactor, e.g. M-shaped in the detonated or shocked regions.

中文翻译：

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正庚烷/空气混合物与水滴的自燃和爆轰特性

摘要 本研究解决了密闭一维反应器中带有水滴的正庚烷/空气混合物的自燃和爆炸特性。气相和液相的欧拉-欧拉公式用于模拟多组分、完全可压缩和反应性多相流。进行了涵盖一系列液滴直径和数量密度的参数研究，以了解不同气体燃烧条件下气相反应前沿的发展和液滴蒸发特性。确定了反应器中四种自燃行为模式，发现它们在很大程度上取决于液滴直径和数量密度。在相对较小的液滴直径和/或数密度下，爆轰是由热点引发的，但在右边界没有发生自燃。当两者或任何一个增加时，自燃发生在右边界，反应前沿可能进一步演变成爆轰或爆燃波。这是因为该区域的温度不均匀性显着增强。此外，液滴直径和数量密度用于量化自燃和爆炸发展的不同模式。对于反应前沿发展过程中的液滴蒸发动力学，观察到各种机制，与由两相之间的速度差异（以液滴雷诺数表征）、高局部气压和液滴温度为主的不同影响有关。