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.
