Mixing Chemical Reactions and Combustion in High-Speed Turbulent Flows

Abstract : Research conducted under the sponsorship of this grant focused on fundamental investigations of mixing, chemical-reaction and combustion processes; in turbulent, subsonic, and supersonic flows. Research on hydrocarbon-combustion was on methane and ethane flames. Flame extinction strain-rate measurements, flame speed, and detailed experiment-simulation comparisons indicate difficulties in modeling of fuel-rich flames. Direct Numerical Simulations (DNS) of axisymmetric unsteady flows in both cold and hot impinging jets were also performed. The research included work on high-speed internal flows of interest to scramjet mixing and combustion, aimed at flow-control and flameholding issues. DNS and Large Eddy Simulations (LES) of Rayleigh-Taylor instability flows studied Reynolds number effects on mixing in this important flow. Advances in high-performance digital-imaging systems were transferred to the laboratory environment enabling measurements unachievable by other means.