This paper describes nitrogen oxide (NOx) measurements from a reacting jet in crossflow (RJICF). The NOx production of the RJICF is controlled by jet stoichiometry, crossflow temperature and composition, and the mixing rates between the fluid streams. Mixing occurs both pre- and post-flame. Pre-flame mixing refers to mixing between the reactant jet and the crossflow prior to combustion and determines the stoichiometry of burning; it is controlled by degree of flame lifting, LO, and the shear layer vortices. Post-flame mixing refers to mixing of these secondary combustion products with the crossflow; it is controlled by the counter-rotating vortex pair. The literature has clearly shown a monotonic increase in RJICF NOx production with its bulk average temperature rise (ΔT) but also indicated significant dependencies on momentum flux ratio (J), jet stoichiometry (ϕ_jet ), and other parameters. Moreover, these parameters are always coupled for a given geometry (e.g., LO varies with ϕ_jet ), and the fundamental influence parameters require clarification. To address this, significant effort was spent in this work on differentiating these coupled effects. NOx measurements were obtained from premixed ethane/methane/air jets injected into a vitiated crossflow of lean combustion products, for ΔT values between 75 and 350 K. Data were obtained at two crossflow temperatures (1350 K and 1410 K), two jet geometries, J values from 6 to 40, and ϕ_jet from 0.8 to 8.0. Ethane/methane ratio was varied to influence flame lifting independent of other parameters. Jet geometry was varied to influence shear layer vortex growth rates and, hence, pre-flame mixing rates. Overall, these data are consistent with the idea that NOx emissions are largely controlled by the stoichiometry at which combustion actually occurs, referred to as ϕ_Flame. ϕ_Flame is influenced by ϕ_jet and pre-flame mixing of the jet and crossflow that, in turn, depend upon LO, nozzle geometry, and crossflow temperature. While this result is expected, it manifests itself in complex manners. For example, NOx levels were observed to be nearly independent of ϕ_jet for a range of conditions, due to the coupled dependence of ϕ_jet and LO. Similarly, NOx emissions are a factor of three lower in the nozzle jet geometry relative to a fully developed exit flow, due to enhanced pre-flame mixing. From a practical point of view, the key implication of these results is its suggestion for minimizing NOx production at a given ΔT – designing injection schemes that enhance flame lifting and shear layer vortex growth rates. Finally, there are indications in the data of additional post-flame mixing effects that require further work to clarify.

本文介绍了横流反应射流（RJICF）中氮氧化物（NOx）的测量。通过喷射化学计量，错流温度和组成以及流体流之间的混合速率来控制RJICF的NOx产生。混合发生在火焰前和火焰后。火焰预混合是指反应物射流与燃烧前的横流之间的混合，它决定了燃烧的化学计量。它受火焰提升程度LO的控制，以及剪切层涡旋。火焰后混合是指这些二次燃烧产物与错流的混合。它由反向旋转的涡流对控制。文献清楚地显示了RJICF NOx产量随其整体平均温度升高（ΔT）单调增加，但也表明对动量通量比（J），喷射化学计量（ϕ _jet ）和其他参数有很大的依赖性。此外，这些参数总是耦合对于给定的几何形状（例如，LO与变化φ_喷射 ），并且需要澄清基本影响参数。为了解决这个问题，在这项工作中花费了大量的精力来区分这些耦合效应。NOx的测量值是从喷射到稀薄燃烧产物的交叉流中的乙烷/甲烷/空气的预混合喷嘴获得的，ΔT值在75至350 K之间。在两个交叉流温度（1350 K和1410 K），两个喷嘴几何形状下获得数据，Ĵ值从6到40，和φ_喷射 从0.8到8.0。改变乙烷/甲烷比率以独立于其他参数影响火焰提升。改变射流的几何形状以影响剪切层涡旋的生长速率，从而影响火焰前的混合速率。总体而言，这些数据与NOx排放很大程度上受实际发生燃烧的化学计量控制（称为ϕ _Flame） 的想法是一致的。φ_火焰受以下因素影响φ_喷射 和喷射的预混合火焰和横流，反过来，取决于LO，喷嘴几何形状，以及横流的温度。虽然可以预期到此结果，但它以复杂的方式表现出来。例如，观察到的NOx水平是几乎独立的φ_喷射 对于一个范围的条件下，由于耦合的依赖性φ_喷射 和LO。类似地，由于增强的预火焰混合，相对于充分发展的出口流，NOx排放是喷嘴射流几何形状的三分之一。从实际的角度来看，这些结果的关键含义是建议在给定的ΔT下将NOx的产生降至最低–设计可提高火焰提升和剪切层涡旋增长率的喷射方案。最后，在数据中还有其他火焰后混合效应的迹象，需要进一步的工作来阐明。