Effects of volatile coatings on the laser-induced incandescence of soot

被引：29

作者：

Bambha, Ray P. ^{[1
]}

Dansson, Mark A. ^{[1
]}

Schrader, Paul E. ^{[1
]}

Michelsen, Hope A. ^{[1
]}

机构：

[1] Sandia Natl Labs, Combust Res Facil, Livermore, CA USA

来源：

APPLIED PHYSICS B-LASERS AND OPTICS | 2013年 / 112卷 / 03期

关键词：

ABSORPTION CROSS-SECTION; BLACK CARBON MEASUREMENTS; LIGHT-SCATTERING; OPTICAL-PROPERTIES; MIXING STATE; WAVELENGTH DEPENDENCE; RADIATIVE ABSORPTION; ELECTRON-MICROSCOPE; PRIMARY PARTICLE; VOLUME FRACTION;

D O I：

10.1007/s00340-013-5463-9

中图分类号：

O43 [光学];

学科分类号：

070207 ; 0803 ;

摘要：

We have measured time-resolved laser-induced incandescence (LII) from combustion-generated mature soot extracted from a burner and (1) coated with oleic acid or (2) coated with oleic acid and then thermally denuded using a thermodenuder. The soot samples were size selected using a differential mobility analyzer and characterized with a scanning mobility particle sizer, centrifugal particle mass analyzer, and transmission electron microscope. The results demonstrate a strong influence of coatings on the magnitude and temporal evolution of the LII signal. For coated particles, higher laser fluences are required to reach signal levels comparable to those of uncoated particles. The peak LII curve is shifted to increasingly higher fluences with increasing coating thickness until this effect saturates at a coating thickness of similar to 75 % by mass. These effects are predominantly attributable to the additional energy needed to vaporize the coating while heating the particle. LII signals are higher and signal decay rates are significantly slower for thermally denuded particles relative to coated or uncoated particles, particularly at low and intermediate laser fluences. Our results suggest negligible coating enhancement in absorption cross-section for combustion-generated soot at the laser fluences used. Apparent enhancement in absorption with restructuring may be caused by less conductive cooling.

引用

页码：343 / 358

页数：16

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