타이틀 |
Soot Precursor Material: Spatial Location via Simultaneous LIF-LII Imaging and Characterization via TEM |
저자 |
Randall L. Vander Wal |
Keyword |
Soot precursor; Laser-induced fluorescence (LIF); Laser-Induced Incandescence (LII); Transmission Electron microscopy (TEM); Polycylic aromatic hydrocarbons |
URL |
http://gltrs.grc.nasa.gov/reports/1996/CR-198469.pdf |
보고서번호 |
NASA CR-198469 |
발행년도 |
1996 |
출처 |
NASA Glenn Research Center |
ABSTRACT |
The chemical and physical transformation between gaseous fuel pyrolysis products and solid carbonaceous soot represents a critical step in soot formation. In this paper, simultaneous two-dimensional LIF-LII images identify the spatial location where the earliest identifiable chemical and physical transformation of material towards solid carbonaceous soot occurs along the axial streamline in a normal diffusion flame. The identification of the individual LIF and LII signals is achieved by examining both the excitation wavelength dependence and characteristic temporal decay of each signal. Spatially precise thermophoretic sampling measurements are guided by the LIF-LII images with characterization of the sampled material accomplished via both bright and dark field TEM. Both bright and dark field TEM measurements support the observed changes in photophysical properties which account for conversion of fluorescence to incandescence as fuel pyrolysis products evolve towards solid carbonaceous soot. |