论文标题
在弱旋转流中闪烁的浮力扩散火焰
Flickering Buoyant Diffusion Flames in Weakly Rotatory Flows
论文作者
论文摘要
在计算和理论上研究了弱旋转流中闪烁的浮力扩散甲烷火焰。突出的计算发现是，闪烁频率非线性随旋转强度数R（最高0.24）而增加，这与甲烷射流速度相比，它测量了旋转速度的相对重要性。这一发现与先前的实验观察结果一致，即在一定程度上旋转流动增强了火焰闪烁。基于对闪烁火焰的涡流动力理解，即火焰闪烁是由浮力引起的环形涡流的周期性脱落引起的，我们为弱旋转流中的闪烁浮力扩散火焰制定了缩放理论。该理论预测，在r = 0时闪烁频率f_0方面，在非零r处的闪烁频率f的增加遵守缩放关系f-f_0〜r^2，这与当前的计算结果非常吻合。在物理学中，外部旋转流量增强了火焰周围的径向压力梯度，而明显的斜压效应为环形涡流的生长提供了额外的来源，因此它们的周期性脱落更快。
Flickering buoyant diffusion methane flames in weakly rotatory flows were computationally and theoretically investigated. The prominent computational finding is that the flicker frequency nonlinearly increases with the rotational intensity number R (up to 0.24), which measures the relative importance of the rotational speed compared with the methane jet speed. This finding is consistent with the previous experimental observations that flame flicker is enhanced by rotatory flows within a certain extent. Based on the vortex-dynamical understanding of flickering flames that the flame flicker is caused by the periodic shedding of buoyancy-induced toroidal vortices, we formulated a scaling theory for flickering buoyant diffusion flames in weakly rotatory flows. The theory predicts that, with respect to the flicker frequency f_0 at R=0, the increase of the flicker frequency f at nonzero R obeys the scaling relation f-f_0~R^2, which agrees very well with the present computational results. In physics, the externally rotatory flow enhances the radial pressure gradient around the flame, and the significant baroclinic effect contributes an additional source for the growth of toroidal vortices so that their periodic shedding is faster.
