Characterization of Scalar Correlations In Turbulent Counterflow Nonpremixed Flames

Purdue University, West Lafayette IN

Investigators

Abstract

This is a study of scalar fluctuations in turbulent jet flames. Spatial and temporal structures are studied in a simplified counterflow geometry. The geometry is conducive to direct comparison between quantitative experimental results and advanced turbulent combustion models such as large-eddy simulations. A modular burner consisting of two opposed jets and providing a range of turbulent flow conditions is used. Quantitative laser diagnostics are applied to a series of flames in this burner to recover the time dependence of OH and CH concentrations, temperature, and mixture fraction. Velocity measurements are obtained on an identical burner at Technische Universitat Darmstadt. A set of simultaneous velocity and concentration measurements are made at Wright-Patterson Air Force Base. Using a simulation technique developed by the investigators, relationships between spatial and temporal correlations are examined quantitatively. Time-series measurements of concentrations of minor species in turbulent jet flames have been made recently. These single-point measurements permit study of time-scale statistics and are analogous to spatial-scale imaging. However, unknown mixing statistics in the jet flames complicate interpretation of these data.