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首页> 外文期刊>Combustion Science and Technology >DYNAMICS OF FLAME PROPAGATION FROM LOCALIZED IGNITION IN RICH HYDROGEN/AIR MIXTURES: EFFECTS OF ELEVATED PRESSURE AND TEMPERATURE
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DYNAMICS OF FLAME PROPAGATION FROM LOCALIZED IGNITION IN RICH HYDROGEN/AIR MIXTURES: EFFECTS OF ELEVATED PRESSURE AND TEMPERATURE

机译：富氢/空气混合物中局部点火引起的火焰传播动力学：压力和温度升高的影响

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摘要

A computational study was conducted on expanding spherical pre-mixed flames to investigate the dynamics of the stretch-affected, one-dimensional, pulsating instability at elevated pressures and temperatures. Rich H_2/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 arid 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 flamm-ability and stability.
机译：对膨胀的球形预混火焰进行了计算研究，以研究受拉伸影响的一维脉动不稳定性在高压和高温下的动力学。使用具有时间依赖性的球形对称代码，使用详细的化学，传输和辐射子模型，研究了富H_2 /空气混合物。研究表明，与局部火焰相比，向外传播的火焰在压力与当量比范围内的不稳定性区域明显缩小，这是由于存在局部着火极限，尽管拉伸引起的脉动改变了其他边界。此外，已经发现了一个以灭绝结束的振荡区域（即使在绝热条件下也不存在于平面火焰中）。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时消光而引起的不稳定区域。有趣的是，这个极限紧挨着点火浓度以下。出于相同的着火/熄火原因，由于增加了可燃性，不稳定区域在高温下会扩大。计算表明，球形膨胀火焰的动力学与平面火焰的动力学显着不同。结果，近极限现象在很大程度上取决于几何形状，从而对可燃性和稳定性的实际考虑产生影响。

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