Temperature Measurements in Reacting Flows Using Time-Resolved Femtosecond Coherent Anti-Stokes Raman Scattering (fs-CARS) Spectroscopy (Postprint)
Abstract
Time-resolved femtosecond coherent anti-Stokes Raman scattering (fs-CARS) spectroscopy of the nitrogen molecule is used for the measurement of temperature in atmospheric-pressure, near-adiabatic, hydrogen-air diffusion flames. The initial frequency-spread dephasing rate of the Raman coherence induced by the ultrafast (85 fs) Stokes and pump beams are used as a measure of gas-phase temperature. This initial frequency-spread dephasing rate of the Raman coherence is completely independent of collisions and depends on the frequency spread of the Raman transitions at different temperatures. A simple theoretical model based on the assumption of impulsive excitation of Raman coherence is used to extract temperatures from time-resolved fs-CARS experimental signals. The extracted temperatures from fs-CARS signals are in excellent agreement with the theoretical temperatures calculated from an adiabatic equilibrium calculation. The estimated absolute accuracy and the precision of the measurement technique are found to be 40 K and 50 K, respectively, over the temperature range 1500-2500 K.
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 01, 2007
- Accession Number
- ADA479621
Entities
People
- James. R. Gord
- Paul J. Kinnius
- Robert P. Lucht
- Sukesh Roy
Organizations
- Air Force Research Laboratory