Yao Zhifeng, Deng Haoxin, Dong Jianfei, Wen Xiaoping, Zhao Weilong, Wang Fahui, Chen Guoyan, Zhang Xinmin, Zhang Qiaosheng
School of Mechanical and Power Engineering, Henan Polytechnic University, Jiaozuo 454003, PR China.
School of Civil Engineering, Henan Polytechnic University, Jiaozuo 454003, PR China.
ACS Omega. 2020 Sep 17;5(38):24906-24915. doi: 10.1021/acsomega.0c03667. eCollection 2020 Sep 29.
The propagation of premix methane/air flames in long half-open ducts with different inclination angles θ between the sidewall and the horizon was numerically investigated using the laminar model. The numerical result was compared with the experimental and theoretical ones to validate the numerical model. The results show that the numerical results are in good agreement with them. The investigation provides the basic understanding of the effects on changing the shape of the ducts to promote the premixed flame combustion. For methane/air, the position where the flame front begins to concave is pushed back with the increase in angle θ. The so-called "tulip" flame even disappeared, if the angle θ is bigger than one certain value. Moreover, the flame propagation speed and pressure are enhanced as the angle θ increases. In addition, the numerical simulation indicates that the burning gas creates an eddy near the tip of the flame, altering the flow field and causing the tulip flame to appear. However, with the angle θ increased, the flame propagation is restrained by the change in sidewalls, resulting in the different flow patterns to suppress the formation of tulip flames and promote flame combustion.
利用层流模型对预混甲烷/空气火焰在侧壁与水平面夹角为不同倾斜角θ的长半开式管道中的传播进行了数值研究。将数值结果与实验结果和理论结果进行比较，以验证数值模型。结果表明，数值结果与它们吻合良好。该研究为理解改变管道形状对促进预混火焰燃烧的影响提供了基础认识。对于甲烷/空气，火焰前沿开始凹陷的位置随着角度θ的增加而后移。如果角度θ大于某个特定值，所谓的“郁金香”火焰甚至会消失。此外，随着角度θ的增加，火焰传播速度和压力会增强。另外，数值模拟表明，燃烧气体在火焰尖端附近产生一个涡旋，改变了流场并导致郁金香火焰出现。然而，随着角度θ的增加，火焰传播受到侧壁变化的抑制，导致不同的流动模式抑制郁金香火焰的形成并促进火焰燃烧。
