DYNAMICS OF FLAME PROPAGATION FROM LOCALIZED IGNITION IN RICH HYDROGEN/AIR MIXTURES: EFFECTS OF ELEVATED PRESSURE AND TEMPERATURE
DYNAMICS OF FLAME PROPAGATION FROM LOCALIZED IGNITION IN RICH HYDROGEN/AIR MIXTURES: EFFECTS OF ELEVATED PRESSURE AND TEMPERATURE
复制标题
富氢/空气混合物中局部点火的火焰传播动力学：升高压力和温度的影响
DOI：
10.1080/00102200590909210
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发表时间：
2003
影响因子：
1.9
通讯作者：
Hong Zhao
中科院分区：
文献类型：
--
作者：
S. Tse;Hong Zhao
摘要对膨胀球形预混火焰进行了计算研究，以研究高温高压下受拉伸影响的一维脉动不稳定性的动力学。丰富的H2/空气混合物进行了研究，使用时间依赖性，球对称的代码与详细的化学，运输和辐射子模型。研究表明，不稳定的区域中的压力与当量比域向外传播的火焰相比，平面火焰由于存在的局部点火极限，尽管拉伸引起的脉动修改其他边界时，显着缩小。此外，还发现了一个以熄灭结束的振荡区域（即使在平面火焰中不存在的绝热条件下）。然而，类似于平面火焰，向外传播的球形火焰中的辐射损失减少了由于瞬态熄灭而导致的不稳定区域。有趣的是，这个极限接近并刚好低于点燃的浓度极限。由于相同的点燃/熄灭原因，不稳定区域在升高的温度下由于增加的可燃性而扩大。计算结果表明，球形膨胀火焰的动力学特性与平面火焰有很大的不同。因此，近极限现象是极其依赖于几何形状的，从而对可燃性和稳定性的实际考虑产生影响。
ABSTRACT A computational study was conducted on expanding spherical premixed flames to investigate the dynamics of the stretch-affected, one-dimensional, pulsating instability at elevated pressures and temperatures. Rich H2/air mixtures were investigated using a time-dependent, spherically symmetric code with detailed chemistry, transport, and radiation submodels. The study shows that the region of instability in the pressure versus equivalence ratio domain for outwardly propagating flames is significantly narrowed when compared with that for planar flames due to the presence of the local ignition limit despite stretch-induced pulsation modifying the other boundary. Moreover, a region of one oscillation ending in extinction (even under adiabatic conditions which are not present in planar flames) has been discovered. However, similar to planar flames, radiative loss in outwardly propagating spherical flames reduces the region of instability due to transient extinction. Interestingly, this limit lies next to and just below the concentration limit for ignition. For the same ignition/extinction reasons, the region of instability is expanded at elevated temperatures due to increased flammability. The calculations show that the dynamics of spherically expanding flames is significantly different than that for planar flames. As a result, the near-limit phenomenon is extremely geometry dependent, thereby having an impact on practical considerations of flammability and stability.