Flame experiments at the Advanced Light Source: New insights into soot formation processes

Hansen N, Skeen SA, Michelsen HA, Wilson KR, Kohse-Höinghaus K. Flame experiments at the Advanced Light Source: New insights into soot formation processes. JOURNAL OF VISUALIZED EXPERIMENTS. 2014;87(87):E51369

Laser-induced fluorescence determination of temperatures in low pressure flames

Rensberger KJ, Jeffries JB, Copeland RA, Kohse-Höinghaus K, Wise ML, Crosley DR. Laser-induced fluorescence determination of temperatures in low pressure flames. Applied Optics. 1989;28(17):3556-3566.Spatially resolved temperatures in a variety of low pressure flames of hydrogen and hydrocarbons burning with oxygen and nitrous oxide are determined from OH, NH, CH, and CN laser-induced fluorescence rotational excitation spectra. Systematic errors arising from spectral bias, time delay, and temporal sampling gate of the fluorescence detector are considered. In addition, we evaluate the errors arising from the influences of the optical depth and the rotational level dependence of the fluorescence quantum yield for each radical. These systematic errors cannot be determined through goodness-of-fit criteria and they are much larger than the statistical precision of the measurement. The severity of these problems is different for each radical; careful attention to the experimental design details for each species is necessary to obtain accurate LIF temperature measurements

Measurement and Modeling of Particle Radiation in Coal Flames

This work aims at developing a methodology that can provide information of in-flame particle radiation in industrial-scale flames. The method is based on a combination of experimental and modeling work. The experiments have been performed in the high-temperature zone of a 77 kWth swirling lignite flame. Spectral radiation, total radiative intensity, gas temperature, and gas composition were measured, and the radiative intensity in the furnace was modeled with an axisymmetric cylindrical radiation model using Mie theory for the particle properties and a statistical narrow-band model for the gas properties. The in-flame particle radiation was measured with a Fourier transform infrared (FTIR) spectrometer connected to a water-cooled probe via fiber optics. In the cross-section of the flame investigated, the particles were found to be the dominating source of radiation. Apart from giving information about particle radiation and temperature, the methodology can also provide estimates of the amount of soot radiation and the maximum contribution from soot radiation compared to the total particle radiation. In the center position in the flame, the maximum contribution from soot radiation was estimated to be less than 40% of the particle radiation. As a validation of the methodology, the modeled total radiative intensity was compared to the total intensity measured with a narrow angle radiometer and the agreement in the results was good, supporting the validity of the used approach

Measurements of rotational energy transfer and quenching in OH A 2[Sigma]+, v'=0 at elevated temperature

Lee MP, Kienle R, Kohse-Höinghaus K. Measurements of rotational energy transfer and quenching in OH A 2[Sigma]+, v'=0 at elevated temperature. Applied Physics B. 1994;58(6):447-457.Total rotational energy transfer rates have been measured at 1330 K for specific rotational levels in the OH A 2[Sigma]+, v'=0 state in collisions with H 20. Rotational levels ranging from N'=0 to 15 were studied. Measurements were performed in the post-flame region of a stoichiometric H2/O2/He flame operating at 25 mbar. Quenching rates following excitation of individual upper rotational states were also measured. The RET and quenching rates both exhibit monotonic decreases with increasing rotational quantum number