Thermodynamic structure of supercritical LOX–GH2 diffusion flames
Thermodynamic structure of supercritical LOX–GH2 diffusion flames
复制标题
超临界LOX-GH2扩散火焰的热力学结构
DOI：
10.1016/j.combustflame.2018.06.016
复制
发表时间：
2018
影响因子：
4.4
通讯作者：
M. Ihme
中科院分区：
文献类型：
--
作者：
D. Banuti;P. Ma;Jean;M. Ihme
在这项研究中，我们使用一维火焰计算和大涡模拟(LES)结果来评估超临界压力下层流氢氧火焰的热力学结构。我们发现在惰性(冷流)和反应性(热流)条件下，真实的流体混合行为是不同的。具体地说，我们证明了跨临界条件下的燃烧并不是由大规模的均匀真实流体混合所主导的：与亚临界雾化类似，超临界纯氧气流经历了从类液体到类气体的明显转变；在理想气体条件下，显著的混合和燃烧主要发生在这种转变之后。一维火焰计算和大涡模拟的联合研究表明，真实流体行为主要局限于大块液氧气流；真实流体混合发生在液氧核心周围的薄层中，其特征是水质量分数限制在3%以内。对一维火焰溶液的参数研究表明，这种结构在很大范围内适用于相关的注射温度和燃烧室压力。为了分析混合引起的局部流体临界点的移动，我们引入了降温降压平面内火焰轨迹的状态空间表示，它允许直接评估局部热力学状态。在火焰中，水增加了局部混合物的临界压力，从而达到亚临界条件。这种超临界条件下有限混合的观点可能会产生更有效的模型，并更好地理解超临界流动的解体模式。
In this study, we evaluate the thermodynamic structure of laminar hydrogen/oxygen flames at supercritical pressures using 1D flame calculations and large-eddy simulation (LES) results. We find that the real fluid mixing behavior differs between inert (cold flow) and reactive (hot flow) conditions. Specifically, we show that combustion under transcritical conditions is not dominated by large-scale homogeneous real-fluid mixing: similar to subcritical atomization, the supercritical pure oxygen stream undergoes a distinct transition from liquid-like to gas-like conditions; significant mixing and combustion occurs primarily after this transition under ideal gas conditions. The joint study of 1D flame computations and LES demonstrates that real-fluid behavior is chiefly confined to the bulk LOX stream; real fluid mixing occurs but in a thin layer surrounding the LOX core, characterized by water mass fractions limited to 3%. A parameter study of 1D flame solutions shows that this structure holds for a wide range of relevant injection temperatures and chamber pressures. To analyze the mixing-induced shift of the local fluid critical point, we introduce a state-space representation of the flame trajectories in the reduced temperature and reduced pressure plane which allows for a direct assessment of the local thermodynamic state. In the flame, water increases the local mixture critical pressures, so that subcritical conditions are reached. This view of limited mixing under supercritical conditions may yield more efficient models and an improved understanding of the disintegration modes of supercritical flows.
影响因子：
3.7
作者：
Pierce, CD;Moin, P
通讯作者：
Moin, P