Broadband ultrafast-laser-absorption spectroscopy for multi-hydrocarbon measurements near 3.3 µm in flames

Abstract

This paper presents the development and application of a broadband ultrafast-laser-absorption-spectroscopy (ULAS) technique operating in the mid-infrared for simultaneous measurements of temperature, methane (CH4), and propane (C3H8) mole fractions. Single-shot measurements targeting the C-H stretch fundamental vibration bands of CH4 and C3H8 near 3.3 µm were acquired in both a heated gas cell up to ≈650K and laminar diffusion flames at 5 kHz. The average temperature error is 0.6%. The average species mole fraction errors are 5.4% for CH4 and 9.9% for C3H8. This demonstrates that ULAS is capable of providing high-fidelity hydrocarbon-based thermometry and simultaneous measurements of both large and small hydrocarbons in combustion gases.