Numerical simulation of emulsified fuel spray combustion with puffing and micro-explosion
Numerical simulation of emulsified fuel spray combustion with puffing and micro-explosion
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DOI：
10.1016/j.combustflame.2010.01.013
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发表时间：
2010-05
影响因子：
4.4
通讯作者：
Hirotatsu Watanabe;Y. Matsushita;H. Aoki;T. Miura
中科院分区：
文献类型：
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作者：
Hirotatsu Watanabe;Y. Matsushita;H. Aoki;T. Miura
研究了乳化燃料喷雾燃烧过程中的膨化和微爆问题。首先，提出了一个膨化数学模型。在所提出的膨化模型中，在膨化过程中的液滴的质量变化率表示的分散水的蒸发速率和由于从液滴表面喷出的细液滴的质量变化率。由于微小液滴的质量变化率与分散水的蒸发率和各液体含量有关。这个模型只有一个实验参数。该模型的主要特点是易于应用于喷雾燃烧的数值模拟。首先，对单液滴的实验结果进行了验证。在实验参数为5.0 ~ 10的范围内，对单个液滴的计算结果与实验结果吻合较好。并对乳化燃料喷雾燃烧过程进行了数值模拟。液滴内部温度的变化决定了膨化和微爆的发生。微爆发生时，液滴迅速转化为水蒸气。将所提出的喷吹模型用于喷雾燃烧数值模拟时，喷吹模型中的实验参数由5.0-10范围内的随机数确定。在不考虑膨化和微爆的情况下，乳化燃料喷雾燃烧的计算结果与实验结果有较大差异，即使在燃烧反应几乎终止的情况下也是如此。同时，考虑微爆炸和膨化时的计算结果与同一位置的实验结果吻合较好。
The purpose of this study was to develop numerical simulation of spray combustion of emulsified fuel with considering puffing and micro-explosion. First, a mathematical model for puffing was proposed. In the proposed puffing model, the rate of mass change of a droplet during puffing was expressed by the evaporation rate of dispersed water and the mass change rate due to fine droplets spouted from the droplet surface. The mass change rate due to fine droplets was related to the evaporation rate of the dispersed water and each liquid content. This model had only one experimental parameter. The essential feature of this model was that it was simple to apply to numerical simulation of spray combustion. First, the validity of the proposed puffing model was investigated with the experimental results for a single droplet. The calculated results for a single droplet with the experimental parameter varying from 5.0 to 10 were in good agreement with the experimental results. Moreover, numerical simulation of spray combustion of emulsified fuel was carried out. The occurrence of puffing and micro-explosion was determined by the inner droplet temperature. When micro-explosion occurred, a droplet changed to vapor rapidly. When the proposed puffing model was used in numerical simulation of spray combustion, the experimental parameter in the puffing model was determined for each droplet by random numbers within the range 5.0–10. The calculated results of spray combustion of emulsified fuel without considering puffing or micro-explosions were different from the experimental results even where combustion reactions were almost terminated. Meanwhile, the calculated results when considering puffing and micro-explosions were in good agreement with experimental results at the same location.