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首页> 外文会议>The 2001 ASME International Mechanical Engineering Congress and Exposition, 2001, Nov 11-16, 2001, New York, New York >EXTINCTION LIMITS OF NONADIABATIC, CATALYST-ASSISTED FLAMES IN STAGNATION-POINT FLOW
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EXTINCTION LIMITS OF NONADIABATIC, CATALYST-ASSISTED FLAMES IN STAGNATION-POINT FLOW

机译：驻点流中非绝热，催化剂辅助火焰的消光极限

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Because combustion is essentially an Arrhenius process, premixed flames generally can only exist within certain parameter ranges, or extinction limits, that correspond to a rate of heat production that is sufficient to sustain the reaction in a given flow geometry. Nonetheless, it is frequently desirable to extend these limits, often for the purpose of increasing fuel efficiency and/or reducing the rate of formation of pollutant species. Another emerging motivation is to allow combustion to be sustained in relatively small volumes, which are characterized by larger surface-to-volume ratios, that would otherwise lead to extinguishing levels of heat loss. Surface catalysts are widely used to achieve such enhancements with respect to efficiency and pollutant formation, and we wish to now consider the role catalysts might play with respect to nonadiabatic flames. The model problem to be studied is illustrated in Figure 1, which depicts a nonadiabatic stretched flame in stagnation-point flow against a catalytic surface. This geometry is similar to that considered by others (cf. Law and Sivashinsky; Giovangigli and Candel; Warnatz et al.), who have analyzed such a problem both analytically and numerically in the absence of heat losses. In addition to previous experimental investigations (cf. Law et al.; Ikeda et al.), this geometry is also suggested by more recent experiments (Gardner et al.) on small-volume combustors. In the latter application, such a combustor (nominally 2500μ X 2500μ X 400μ) is fed by an inlet tube that blows against a catalytic surface (platinum mounted on a titanium/silicon wafer) and is vented by one or more outlet ports on either the opposite face (shortest dimension) or sides. In those experiments, it was demonstrated, following ignition by the heated catalytic surface, that a nearly flat flame could be sustained under the inlet port, close to the catalytic surface, without further heat addition. In the absence of the catalyst, the level of heat loss was apparently sufficient to extinguish the flame.
机译：因为燃烧本质上是一个阿累尼乌斯过程，所以预混火焰通常只能存在于一定的参数范围或消光极限内，这些参数范围或消光极限对应于足以在给定的流动几何条件下维持反应的产热速率。尽管如此，经常期望扩展这些限制，通常是为了提高燃料效率和/或减少污染物种类的形成速率。另一个新出现的动机是允许以相对较小的体积维持燃烧，其特征在于较大的表面积与体积之比，否则将导致扑灭热量损失。表面催化剂被广泛用于实现效率和污染物形成方面的这种增强，我们现在希望考虑催化剂在非绝热火焰中可能发挥的作用。要研究的模型问题在图1中进行了说明，该图描绘了停滞点流对催化表面的非绝热拉伸火焰。这种几何形状与其他人（参见Law和Sivashinsky； Giovangigli和Candel； Warnatz等人）所考虑的相似，他们在没有热损失的情况下，通过分析和数值分析了这一问题。除了以前的实验研究（参见Law等人； Ikeda等人），这种几何形状还由最近的小体积燃烧器实验（Gardner等人）提出。在后一种应用中，这种燃烧器（标称值为2500μX2500μX400μ）由进气管进料，该进气管吹向催化表面（安装在钛/硅晶片上的铂），并通过一个或多个排气孔排空。对面（最短尺寸）或侧面。在那些实验中，证明了在被加热的催化表面点火之后，可以在靠近催化表面的进气口下方维持接近扁平的火焰，而无需进一步添加热量。在没有催化剂的情况下，热损失的水平显然足以扑灭火焰。

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