Chemical Reactions in Turbulent Mixing Flows

The purpose of this research is to conduct fundamental investigations of turbulent mixing, chemical reaction and combustion processes in turbulent, subsonic and supersonic flows. The program during this reporting period was comprised of several parts: a. an experimental effort, b. a numerical simulation effort, and c. an effort to develop instrumentation and diagnostics; flow and combustion facilities; and data-acquisition systems. The latter as dictated by the specific needs of the experimental part of the program. Our approach in this research has been to carry out a series of detailed theoretical and experimental studies of turbulent mixing in primarily in two, well-defined, fundamentally important flow fields: free-shear layers and axisymmetric jets. To elucidate molecular transport effects, experiments and theory concern themselves with both reacting and non-reacting flows of liquids and gases, in fully-developed turbulent flows, i.e., in moderate to high Reynolds number flows. A criterion for fully-developed turbulence was recently developed and will be presented below. The computational studies are, at present, focused at fundamental formulation and implementation issues pertaining to the computational simulation of both compressible and incompressible flows characterized by strong fronts, such as shock waves and flames. Our diagnostic development efforts have recently been focused on improving the signal-to-noise ratio of flow images, in both gas- and liquid-phase flows, as well as the continuing development of data-acquisition electronics to meet very high-speed, high-volume data requirements; the acquisition of single, or pairs, of two-dimensional images in rapid succession; and the acquisition of data from arrays of supersonic flow sensors.