CARS thermometry in fuel-rich combustion zones

CARS Temperature Measurements in Sooting, Laminar Diffusion Flames

“…Analysis of experimental CARS spectra was carried out with a two parameter, least-squares fitting routine. Details of this analysis for the present case can be found in Hall and Boedeker (1984). The spectra were analysed using the standard convolution given by Yuratich (1979).…”

“…As mentioned above, the present spectra are acquired directly by the computer and are analyzed with a two parameter least-squares fitting technique. Recent work by Hall and Boedeker (1984) in an ethylene-air diffusion flame has shown that nonresonant susceptibility of hydrocarbon fuels can affect the analysis of experimental spectra in fuel-rich regions well beyond the lip of the burner and essentially throughout the region inside the flame front. The extent of the effect was not clearly evident in the Eckbreth and Hall work.…”

“…Previously reported temperatures were high in fuel rich regions due to nonresonant susceptibility effects. We have shown recently (Hall and Boedeker, 1984) that these effects can be accounted for by introduction of a two parameter algorithm.…”

Coherent Anti-Stokes Raman Spectroscopy measurements of temperature fluctuations in turbulent natural gas-fueled piloted jet diffusion flames

“…A major problem in diffusion flames is the large nonresonant susceptibility (Xnr) in the fuel-rich parts of the flame. A two-parameter fit (temperature and the ratio of the probed species mole fraction to the average molecular background susceptibility) is then essential to avoid substantial temperature overestimate [23]. With a two-parameter fit, the inferred temperature is largely unaffected by the initial value of the unknown instantaneous background susceptibility or composition, as long as there is a sufficient resonant signal.…”

High-speed N2-CARS thermometry

“…With a turbulent stoichiometric Bunsen-flame located at the CARS probe volume, we measured temperature histograms for several repetition rates and fixed fuel/oxidizer flows• The spectra were recorded in the post-flame region approximately 10 cm above the burner surface• Figure 6 shows a normalized single-pulse CARS spectrum measured at 80 Hz together with the library spectrum of 2070 K. Calculating this library of CARS-spectra we used a constant value of 1 2 *'NR It has been shown that the nonresonant • A, N2" susceptibility in stoichiometric flames does not depend strongly on the chemical composition [2]. Single-pulse intensities of the spectra were about 700 counts at maximum.…”