Flame Thermometry Measurements in a Jet Diffusion Flame at 5 kHz using Femtosecond Coherent Anti-Stokes Raman Scattering

摘要

Single-laser-shot temperature measurements at 5 kHz are performed in a jet diffusion flame using femtosecond (fs) coherent anti-Stokes Raman scattering (CARS). Measurements are performed at various heights and radial locations within the jet diffusion flame. The use of a high repetition rate femtosecond laser system and an electron multiplying charged coupled device (EMCCD) camera allows for data to be recorded at 5 kHz. High repetition rates are required to resolve the temperature fluctuations that occur in diffusion flames due the Kelvin-Helmholtz type instabilities and vortices that occur due to interaction of hot combustion gases and cold ambient air. Measurements are reported in a near adiabatic Hencken burner flame with standard deviations as low as 2.1%. Single laser shot temperature measurements are reported in the jet diffusion flame between 400 - 2500 K. These measurements provide better insight into instabilities present in diffusion flames and demonstrate the usefulness of this diagnostic technique to investigate other turbulent combustion phenomena.