论文标题
燃烧的阳性空气流烷的3D粒子模拟
3D particle simulations of positive air-methane streamers for combustion
论文作者
论文摘要
流媒体排放可以用作血浆辅助燃烧的反应性物种的主要来源。在这项研究中，我们研究了1个bar和300 K的化学计量表空气 - 甲烷混合物中的阳性流媒体，其具有三维的电子粒子模型。我们首先讨论合适的电子散射横截面，并将光离子机理扩展到空气甲烷混合物。我们讨论，添加9.5％的甲烷将电子传输和反应系数基本不变，但是它在很大程度上抑制了光电离，并缩短了光子平均自由路径。这导致了（1）加速流式分支，（2）彩流器头处的较高电场增强，（3）较低的内部电场和（4）（4）流媒体通道中较高的电子密度。我们还计算了在12.5和20 kV/cm的背景电场中阳性流媒体演变中沉积的时间集成能量密度。我们发现沉积的能量密度的典型值在0.5-2.5 kj/m $^{3} $范围内，其长度为5 mm的电离内部内部；该值与此处应用的电场相当独立。最后，我们发现沉积在非弹性电子散射过程中的能量主要产生反应性氮种类：n $ _2 $三重态状态和N，以及O和H自由基。 h $ _2 $和o $ _2 $ singlet状态的生产也发生了不太明显。我们对反应性物种的主要产生的计算可以在全球化学模型中使用。
Streamer discharges can be used as a primary source of reactive species for plasma-assisted combustion. In this research we investigate positive streamers in a stoichiometric air-methane mixture at 1 bar and 300 K with a three-dimensional particle-in-cell model for the electrons. We first discuss suitable electron scattering cross sections and an extension of the photoionization mechanism to air-methane mixtures. We discuss that the addition of 9.5% methane leaves electron transport and reaction coefficients essentially unchanged, but it largely suppresses photoionization and shortens the photon mean free path. This leads to (1) accelerated streamer branching, (2) higher electric field enhancement at the streamer head, (3) lower internal electric fields, and (4) higher electron densities in the streamer channel. We also calculate the time-integrated energy density deposited during the evolution of positive streamers in background electric fields of 12.5 and 20 kV/cm. We find typical values of the deposited energy density in the range of 0.5-2.5 kJ/m$^{3}$ within the ionized interior of streamers with a length of 5 mm; this value is rather independent of the electric fields applied here. Finally we find that the energy deposited in the inelastic electron scattering processes mainly produces reactive nitrogen species: N$_2$ triplet states and N, but also O and H radicals. The production of H$_2$ and O$_2$ singlet states also occurs albeit less pronounced. Our calculation of the primary production of reactive species can for example be used in global chemistry models.
