The Effects of Heat Release on the Flow Structure of Planar Hydrogen Diffusion Flames

热释放在湍流结构和混合过程中的作用尚未完全确定。理解这一现象对我们处理湍流反应流的能力是非常重要的。这个提议提出了一个研究计划，如果成功的话，将通过实验确定热释放效应，对湍流燃烧领域贡献重要的知识，使用平面槽式燃烧器测量非预混氢/空气火焰。提出的工作的目的是记录在混合有限条件下高水平的热量释放对平面射流火焰的大规模湍流结构的影响。这项计划是在桑迪亚大学做博士后时所做工作的延伸。本文研究了氢/空气圆形射流火焰的近场结构。用激光诱导荧光（LIF）显示OH激发下的反应区，用种子丙酮激发标记燃料。与非反应情况相比，反应情况下的流场发生了相当大的变化；湍流层化明显，混合层生长速度大大降低；热反应区出现稳定局部湍流波动，导致反应区和湍流区相互独立。为了简化对这些实验的解释，PI提出了一系列实验，其中将使用更简单的几何剪切流（由平面混合层提供），以期为高热量释放对流动的改变提供更清晰的证据。平面射流喷嘴流动装置、流动可视化技术（OH和丙酮PLIF）以及陶瓷粒子的平面Mie散射将用于本研究。将对冷流和热流进行比较。这项研究的一个主要目标是将燃烧射流的大尺度结构与非燃烧射流的大尺度结构进行比较。这项研究工作可能会对理解湍流反应流做出重要贡献。

ABSTRACT -- CTS-9319136 CLEMENS The role of heat release on the structure of turbulence and the mixing process has not been fully established. The understanding of this phenomenon is very important to our capability of dealing with turbulent reacting flows. This proposal presents a research plan, that if successful, will contribute important knowledge to the field of turbulent combustion by experimentally determining heat release effects, measured on non-premixed Hydrogen/Air flames using a planar slot burner. The objective of the proposed work is to document the influence of high levels of heat release under mixing limited conditions, on the large-scale turbulent structure of planar jet flames. The proposed effort is an extension of work done at Sandia while the PI was a post doctoral fellow. In this study, the near field structure of Hydrogen/Air round jet flames was investigated. Laser Induced Fluorescence (LIF) was used to visualize the reaction zone by excitation of OH and the fuel was marked by excitation of seeded acetone. Considerable modification of the flow field in the reacting case was observed as compared to the non-reacting case; turbulence appeared to be significantly laminarized and the growth rate of the mixing layer greatly reduced; the hot reaction zone appeared to stabilize the local turbulent fluctuations, resulting in an independence of the reacting and turbulent regions. In order to simplify the interpretation of these experiments, the PI has proposed a series of experiments in which a simpler geometry shear flow (provided by a planar mixing layer) will be used to hopefully yield clearer evidence for the modifications to the flow by high levels of heat release. A planar jet nozzle flow facility together with flow visualization techniques including OH and acetone PLIF and planar Mie scattering of seeded ceramic particles will be used in this proposed investigation. Comparisons of cold and hot flows will be made. A major goal of the study will be to compare the large-scale structure of burning jets to the structure of their non-burning counterparts. This research effort could lead to important contributions in the understanding of turbulent reacting flows.