预混火焰在封闭狭缝内传播动力学研究

Study on the Dynamics of Premixed Flame Propagation in a Confined Narrow Gap

本文构建了一个封闭圆盘狭缝空间的一维平面火焰动力学模型,研究了存在壁面热损失条件下可燃混合物在封闭的圆盘狭缝定容装置内火焰的传播特性。模型预测结果与实验结果定性地吻合。模型表明显示,壁面散热降低火焰传播速度的机制在于其使高温已燃气体向低温未燃气体方向的膨胀能力减小,导致火焰前锋的当地流场速度降低,而且同时降低了火焰温度和燃烧反应速率。因此增大初始压力或掺氢气等低活化能的反应物能够有效降低壁面散热的不利影响。该计算模型能够丰富微小尺度封闭空间内火焰传播相关理论,并提供在微小封闭空间内提高火焰传播速度和燃烧效率的理论依据和调控手段。

An one-dimensional planar fame propagation dynamics model in a confined narrow gap of disc shape was developed in this work.And the fame propagation characteristics of combustible mixture in the closed disc-shape narrow gap with the heat loss through walls were studied.The model indicated that wall heat dissipation reduces the flame propagation velocity by reducing the expansion of the high-temperature burnt gas to the low temperature gas,leading to a decrease of the velocity in the fow field across the fame front,and also the fame temperature and the chemical reaction rate.Therefore,increasing the initial pressure or blending reactants with low activation energy such as hydrogen,can effectively reduce the negative effect of wall heat dissipation.The developed theoretical model enriched the theory of fame propagation in micro-scale confined spaces,and also provide corresponding theories and controlling methods for improving flame propagation speed and combustion efficiency.