This paper describes NOx measurements from reacting jets in crossflow (RJICF). This work is motivated by interest in axial staging of combustion as a means of reducing NOx emissions at high flame temperatures (>1900 K), where thermal NOx production rates are high. In this approach, the majority of the fuel is burned in a conventional lean-premixed flame, but additional fuel is injected from the combustor walls into the vitiated flow further downstream. The NOx emissions of RJICF are influenced by the secondary fuel jet stoichiometry, jet/crossflow mixing before combustion, as well as secondary combustion product mixing with the bulk product stream. In turn, jet/crossflow mixing is controlled by the hydrodynamic stability of the jet, as well as degree of flame lifting. A key challenge in understanding fundamental factors influencing NOx is decoupling the effect of bulk temperature rise due to the RJICF (∆T), JICF momentum flux ratio (J), and JICF stoichiometry (ϕ_Jet), as they cannot be varied independently. As such, significant effort was made in developing a test matrix to differentiate their effects. Measurements reported here were obtained from rich premixed methane/air jets injected into a varying temperature (1650 K–1800 K) vitiated crossflow, for bulk temperature rises from 20 K–290 K, J values from 1.3–4.4, and ϕ_Jet values from 1–9. These measurements show that NOx emissions monotonically increase with ∆T, as noted in prior studies, but the data reported here are able to differentiate the effects of ∆T and other parameters. In fact, for a given ΔT value, NOx values can vary by 2X depending upon other parameters. For example, the lifting of the flame (LO), which varies with ϕ_Jet and J has significant effects on NOx emissions. These data suggest that the key fundamental JICF parameters influencing NOx emissions are ∆T, ϕ_Jet, J, and LO.

本文描述了横流中反应射流（RJICF）的NOx测量。这项工作是出于对轴向燃烧阶段的兴趣，作为减少高火焰温度（> 1900 K）时NOx排放的一种手段，在此情况下，NOx的热生产率很高。在这种方法中，大多数燃料在常规的稀薄预混火焰中燃烧，但是额外的燃料从燃烧室壁喷射到更下游的真空流中。RJICF的NOx排放受到二次燃料喷射化学计量，燃烧前的喷射/错流混合以及二次燃烧产物与散装产物流的混合的影响。反过来，射流/错流混合则由射流的流体力学稳定性以及火焰提升程度。理解影响NOx的基本因素的一个关键挑战是将由于RJICF（∆T），JICF动量通量比（J）和JICF化学计量比（ϕ_Jet）引起的整体温度上升的影响解耦，因为它们不能独立地变化。因此，在开发测试矩阵以区分其效果方面付出了巨大的努力。此处报告的测量值是从注入到不同温度（1650 K–1800 K）的横流中的丰富的预混合甲烷/空气喷嘴获得的，整体温度从20 K–290 K升高，J值从1.3–4.4，ϕ_喷射值从1–9。这些测量结果表明，如先前研究中所述，NOx排放随ΔT单调增加，但此处报告的数据能够区分ΔT和其他参数的影响。实际上，对于给定的ΔT值，NOx值可以根据其他参数变化2倍。例如，随lifting _Jet和J变化的火焰升力（LO）对NOx排放有显着影响。这些数据表明，影响NOx排放的关键JICF基本参数为∆T，ϕ _Jet，J和LO。