Effect of relative humidity on heat transfer across the surface of an evaporating water droplet in airflow
Effect of relative humidity on heat transfer across the surface of an evaporating water droplet in airflow
复制标题
相对湿度对气流中蒸发水滴表面传热的影响
DOI：
10.1017/s0022112009005862
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发表时间：
2009
影响因子：
3.7
通讯作者：
S. Komori
中科院分区：
文献类型：
--
作者：
R. Kurose;A. Fujita;S. Komori
采用三维直接数值模拟（DNS）方法，研究了空气中球形水滴蒸发过程中水滴内外的流动，以及相对湿度对水滴与周围空气间传热的影响。初始空气温度被设定为比初始液滴温度高15K。结果表明，局部蒸发热损失在液滴前部最大，由前部到后部逐渐减小，且随着雷诺数的增大，后部的减小趋势更加明显。这是因为蒸发速率在后表面上被液滴后面的流动分离所抑制。液滴温度在低湿度条件下降低，而在高湿度条件下升高。这种差异是由液滴表面处的蒸发热损失和来自环境空气的对流热增益的热平衡引起的。
A three-dimensional direct numerical simulation (DNS) is applied to flows inside and outside an evaporating spherical water droplet in air, and the effect of relative humidity on the heat transfer between the droplet and ambient air is investigated. The initial air temperature is set to be 15 K higher than the initial droplet temperature. The results show that the local evaporation heat loss indicates the maximum on the front of the droplet and decreases on going from the front to the rear, and the reduction on the rear becomes marked for high-droplet Reynolds numbers. This is because the evaporation rate is suppressed on the rear surface by the presence of flow separations behind the droplet. The droplet temperature decreases in the low-humidity condition, whereas it increases in the high-humidity condition. This difference is caused by the heat balance of evaporation heat loss and convective heat gain from ambient air at the droplet surface.