High spatial resolution laser cavity extinction and laser-induced incandescence in low-soot-producing flames
Abstract
Accurate measurement techniques for in situ determination of soot are necessary to understand and monitor the process of soot particle production. One of these techniques is line-of-sight extinction, which is a fast, low-cost and quantitative method to investigate the soot volume fraction in flames. However, the extinction-based technique suffers from relatively high measurement uncertainty due to low signal-to-noise ratio, as the single-pass attenuation of the laser beam intensity is often insufficient. Multi-pass techniques can increase the sensitivity, but may suffer from low spatial resolution. To overcome this problem, we have developed a high spatial resolution laser cavity extinction technique to measure the soot volume fraction from low-soot-producing flames. A laser beam cavity is realised by placing two partially reflective concave mirrors on either side of the laminar diffusion flame under investigation. This configuration makes the beam convergent inside the cavity, allowing a spatial resolution within 200 μm, whilst increasing the absorption by an order of magnitude. Three different hydrocarbon fuels are tested: methane, propane and ethylene. The measurements of soot distribution across the flame show good agreement with results using laser-induced incandescence (LII) in the range from around 20 ppb to 15 ppm.Publisher
Springer Science and Business Media LLCJournal
Applied Physics BDOI
10.1007/s00340-015-6156-3Additional Links
https://link.springer.com/article/10.1007/s00340-015-6156-3https://www.repository.cam.ac.uk/handle/1810/249034
Type
ArticleLanguage
enISSN
0946-2171EISSN
1432-0649ae974a485f413a2113503eed53cd6c53
10.1007/s00340-015-6156-3