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

摘要--CTS-9319136克莱门斯热释放对湍流结构和混合过程的作用尚未完全确定。对这一现象的理解对于我们处理湍流反应流的能力是非常重要的。这项建议提出了一项研究计划，如果成功，将通过实验确定放热效应，从而为湍流燃烧领域贡献重要的知识，该放热效应是使用平面缝隙燃烧器在非预混氢/空气火焰上测量的。这项工作的目的是记录混合受限条件下的高水平放热对平面喷流火焰大尺度湍流结构的影响。拟议的工作是桑迪亚研究所在PI担任博士后研究员期间所做工作的延伸。本文研究了氢/空气圆喷流火焰的近场结构。用激光诱导荧光(LIF)观察了OH激发下的反应区，用种子丙酮激发标记了燃料。与非反应情况相比，反应情况下的流场有了很大的变化；湍流明显分层，混合层的生长速度大大降低；热反应区似乎稳定了局部的湍流波动，导致了反应和湍流区域的独立。为了简化对这些实验的解释，PI提出了一系列实验，在这些实验中，将使用更简单的几何剪切流(由平面混合层提供)，以有望为高水平热释放对流动的修改提供更清晰的证据。在这项研究中，将使用平面喷嘴流动装置和流动显示技术，包括羟基和丙酮的PLIF和晶种陶瓷颗粒的平面Mie散射。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喷气式飞机的大尺度结构与非燃烧喷气式飞机的结构进行比较。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.