Spray dynamics as a multi-scale process
Spray dynamics as a multi-scale process
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喷雾动力学作为多尺度过程
DOI：
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发表时间：
2008
期刊：
影响因子：
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通讯作者：
S. Begg
中科院分区：
文献类型：
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作者：
S. Sazhin;S. Martynov;F. Kaplanski;S. Begg
由于其复杂性，在大多数情况下，考虑到所有空间和时间尺度的贡献，对喷雾过程进行分析是不可行的。大多数应用中使用的方法基于对不同规模的流程的单独分析以及对这些流程之间的联系的分析。该方法被证明可用于分析柴油发动机条件下的喷雾破碎和渗透，以及汽油发动机条件下的涡环结构。回顾了传统的 WAVE、TAB、随机和修正的 WAVE（考虑瞬态效应）模型。有人指出，后一种模型导致对类似柴油机条件下的喷雾渗透的预测最接近实验观察到的情况。在类似汽油机的条件下，喷雾穿透往往伴随着涡环结构的形成，其空间尺度与喷雾穿透的规模相当。涡环质心速度的一般表达式可以进行短时间和长时间的简化，后者的简化特别简单并且对于工程应用很有用。涡环的厚度表示为l=atb，其中a是任意常数且1/4≤b≤1/2。 b=1/2和b=1/4时的情况分别指层流和湍流涡环。该模型与汽油发动机条件下涡环结构的观察兼容。
The analysis of the processes in sprays, taking into account the contribution of all spatial and temporal scales, is not feasible in most cases due to its complexity. The approach used in most applications is based on separate analysis of the processes at various scales, and the analysis of the link between these processes. This approach is demonstrated for the analysis of spray break-up and penetration in Diesel engine-like conditions, and vortex ring-like structures in gasoline engine-like conditions. The conventional WAVE, TAB, stochastic and modified WAVE (taking into account transient effects) models are reviewed. It is pointed out that the latter model leads to the prediction of spray penetration in Diesel engine-like conditions closest to the one observed experimentally. In gasoline engine-like conditions, spray penetration is often accompanied by the formation of vortex ring-like structures, the spatial scale of which is comparable with the scale of spray penetration. The general expression of the velocity of the vortex ring centroid can be simplified for short and long times, the latter simplification being particularly simple and useful for engineering applications. The thickness of the vortex ring is expressed as l = atb, where a is an arbitrary constant and 1/4 ≤ b ≤ 1/2. The cases when b = 1/2 and b = 1/4 refer to laminar and turbulent vortex rings respectively. The model is compatible with the observation of vortex ring-like structures in gasoline engine-like conditions.