WIDECARS multi-parameter measurements in premixed ethylene–air flames using a wavelength stable ultrabroadband dye laser

Abstract

Width-increased dual-pump enhanced coherent anti-Stokes Raman spectroscopy (WIDECARS) measurements were used to determine the temperature and major species mole fractions in laminar, premixed, ethylene-air flames operating at atmospheric pressure. Conventional ultrabroadband dye lasers for WIDECARS, which use Pyrromethene dyes, have historically suffered from day-to-day wavelength shifting. To overcome this problem, a new ultrabroadband dye laser was developed in this study to provide a stable wavelength and power generation. A new dye laser pumping scheme and a mixture of Sulforhodamine 640, Kiton Red 620, and Rhodamine 640, was used to generate the desired FWHM ${\sim}{15}\;{\rm nm}$∼15nm (${410}\;{{\rm cm}^{ - 1}}$410cm^-1) bandwidth. The WIDECARS measured mole fraction ratios of ${{\rm CO}_2}$CO₂, CO, and ${{\rm H}_2}$H₂ with ${{\rm N}_2}$N₂ agreed well with chemical equilibrium calculations.