Experimental Characterization of Chain-Aggregate Aerosol by Electrooptic Scattering

Abstract

A technique combining the electric field-induced alignment and the transient light scattering was applied to characterize Fe20, chain-aggregate aerosols. Particles were exposed to a pulsed square electric field with strengths up to 2.5 kV/cm. Rotational diffusion constants of the particles were obtained from the decay rate of the relative change in light scattering intensity due to orientation of particles after the removal of

In Situ Dynamic Measurement of Polydisperse Chain Aggregate Aerosols Using Photocorrelation Spectroscopy Technique

“…From Table 1, we can determine that the average length of chain aggregates increases along with the liquid carbonyl temperature. This trend consistent with some earlier work done by Kasper, Fu, and Cheng using different techniques (Kasper, 1982b;Fu, 1989;Cheng, 1991b). Table 2 shows the variation of the average length of chain aggregates along with the gas flow dilution ratio changes while the bath temperature is fixed at -20'.…”

Combustion fume structure and dynamics. Final report

“…Alignment may persist for particles greater than 1000 nm. Similar arguments concerning alignment in electrical fields in the DMA also suggest that alignment can be important for particles greater than 100 nm [48]. In the present study, the lengths L of 10 thermophoretically deposited agglomerates (dm -200nm) were measured with the TEM stage tilted at 0" and 30".…”

Light Scattering Shape Diagnostics for Nano-Agglomerates

“…For the iron oxide chain aggregates, explicit results for the change in the scattering intensity are not given. However, data from Figure 5 of Chen et al (1991) for 2.9 μm long chains with 0.06 μm primary sphere diameters indicates a seven fold (700%) increase in the light scattering intensity.…”

“…There have been measurements of the light scattering by nano-agglomerates, both randomly oriented and partially aligned in an electric field. These measurements have been made for smoke from a variety of fuels, smoke from Kuwait oil fires, and iron oxide chain-aggregates by Chen et al (1991); Weiss et al (1992); and Colbeck et al (1997), respectively. For both of the smoke studies, the authors found that for the fractal agglomerate smoke (soot), the total scattering coefficient increased by 20% to 70% for the aligned soot relative to the randomly oriented soot.…”