Finite-rate chemistry effects in a Mach 2 reacting flowUV spontaneous vibrational Raman scattering and laser-induced predissociative fluorescence (LIPF) are combined and applied to a supersonic flame. For the first time, simultaneous measurements of temperature, major species (H2, O2, N2, H2O), and minor species (OH) concentrations are obtained with a 'single' excimer laser in a supersonic-lifted hydrogen-air diffusion flame. In the supersonic flame, a small amount of reaction occurs upstream of the lifted flame base, due to shock wave interactions and mixing with hot vitiated air. The strong turbulent mixing and high total enthalpy fluctuations lead to nonequilibrium values of temperature, and major and minor species concentrations. Combustion occurs farther downstream of the lifted region where slow three-body recombination reactions result in superequilibrium OH concentrations that depress the temperatures below their equilibrium values. Farther downstream, ambient air entrainment contaminates flame properties.
Document ID
19910057127
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Cheng, T. S. (Vanderbilt Univ. Nashville, TN, United States)
Wehrmeyer, J. A. (Vanderbilt Univ. Nashville, TN, United States)
Pitz, R. W. (Vanderbilt University Nashville, TN, United States)
Jarrett, O., Jr. (Vanderbilt Univ. Nashville, TN, United States)
Northam, G. B. (NASA Langley Research Center Hampton, VA, United States)