论文标题
可变形燃油液滴的燃烧和蒸发
Combustion and Evaporation of Deformable Fuel Droplets
论文作者
论文摘要
\ textit {本研究的重点是在对流流下隔离的自由变形燃料液滴的燃烧和蒸发。液滴形状通过在中等雷诺数上改变韦伯数来修改。简化的化学反应机制用于燃烧建模。} \ textIt {直接数值模拟（DNS）结果显示韦伯数量对纯蒸发和燃烧病例的总蒸发率（$ \ dot {M} $）的净积极作用。 $ \ dot {m} $的增强功能的更高韦伯数量达到$ 9 \％$的燃烧。观察到随时间生长的非球形包膜火焰。对于这种火焰类型的Damköhler数高于1，与蒸发相比，导致反应速率更快。因此，燃烧过程被认为不受液滴形状的影响。进行3-D和2D燃烧结果之间的另一个比较，以了解2-D研究是否可以反映出此问题的正确物理方面。发现2-D中的局部蒸发通量为$ 42.5 \％$降低，因为在液滴表面附近的温度梯度较低，以相同的流入速度。在2D中，液滴的变形显着差异，这会影响边界层的发育和尾流。看到这会影响液滴下游的火焰形状。因此，二维模拟无法恢复正确的行为。}
\textit{This study focuses on combustion and evaporation of an isolated freely deforming fuel droplet under convective flow. The droplet shape is modified by varying Weber number at moderate Reynolds numbers. A simplified chemical reaction mechanism is used for combustion modelling.} \textit{The Direct Numerical Simulation (DNS) results show a net positive effect of Weber number on total evaporation rate ($\dot{m}$) for both pure evaporation and combustion cases. The enhancement in $\dot{m}$ for higher Weber number reaches upto $9 \%$ for combustion. A non-spherical envelope flame is observed which grows with time. The Damköhler number is higher than 1 for this flame type which leads to faster reaction rates in comparison to evaporation. Hence, the combustion process is seen to be unaffected by droplet shape. An additional comparison between 3-D and 2-D combustion results is performed to understand if 2-D studies can reflect the right physical aspects of this problem. It is found that local evaporation flux in 2-D is $ 42.5 \%$ lower due to lower temperature gradients near the droplet surface for the same inflow velocity. The deformation of droplet is significantly different in 2-D which affects the boundary layer development and the wake flow. This is seen to affect the flame shape at the downstream of droplet. Hence, the 2-D simulations do not recover the correct behaviors.}
