An investigation of premixed flame propagation in a closed combustion duct with a 90 degrees bend
An investigation of premixed flame propagation in a closed combustion duct with a 90 degrees bend
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90度弯封闭燃烧管道内预混火焰传播研究
DOI：
10.1016/j.apenergy.2014.07.071
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发表时间：
2014
期刊：
影响因子：
11.2
通讯作者：
Sun Jinhua
中科院分区：
文献类型：
--
作者：
Xiao Huahua;He Xuechao;Duan Qiangling;Luo Xisheng;Sun Jinhua
本文采用实验和数值模拟的方法，研究了90°弯曲封闭燃烧管内预混火焰的传播和压力动态特性，为进一步了解弯曲燃烧室内预混燃烧过程提供了理论依据。在实验中，高速纹影摄影被用来记录火焰形状和位置随时间的变化。压力传感器用于测量腔室中的压力升高。在数值模拟中，动态加厚模型被应用到等温和绝热壁面条件下的火焰动力学允许详细的洞察。结果表明，火焰在水平直截面上演化为明显的郁金香形，数值计算中呈现四舌状。在弯曲中，下舌控制火焰传播。火焰在郁金香消失后保持凹进，并在弯曲处沿沿着环绕。研究发现，壁面热损失对燃烧动力学有很大的影响，包括火焰前锋的演变和压力建立。等温壁面燃烧动力学数值模拟结果与实验结果吻合较好。此外，分析表明，尽管存在弯曲，水平段的火焰机理与直管段的火焰机理是一致的。
In this work, the premixed flame propagation and pressure dynamics in a closed combustion tube with a 90° bend are investigated using experiment and numerical simulations to provide further knowledge of premixed combustion process in a curved chamber. In the experiment, high-speed schlieren photography is employed to record the changes in flame shape and position as a function of time. And a pressure transducer is used to measure the pressure rise in the chamber. In the numerical simulations, a dynamically thickened model is applied to allow a detailed insight into the flame dynamics under both isothermal and adiabatic wall conditions. It is revealed that the flame evolves into a notable tulip shape in the straight horizontal section which takes on a four-tongue appearance in the numerical calculations. The lower tongues dominate the flame propagation in the bend. The flame remains concaved after the tulip disappearance and rounds along the inner wall in the bend. It is found that the heat losses to the walls have a great impact on the combustion dynamics, including the flame front evolution and pressure build-up. The numerical combustion dynamics with isothermal walls agrees well with the experimental results. Furthermore, the analytical analysis demonstrates that the flame mechanism in the horizontal section is consistent with that in a straight duct in spite of the presence of the bend.