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Article
Influence of soot aggregate structure on particle sizing using laser-induced incandescence: importance of bridging between primary particles
Soot aggregates formed in combustion processes are often described as clusters of carbonaceous particles in random fractal structures. For theoretical studies of the physical properties of such aggregates, the...
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Article
Time-domain measurements of S-branch N2–N2 Raman linewidths using picosecond pure rotational coherent anti-Stokes Raman spectroscopy
Time-resolved dual-broadband picosecond pure rotational CARS has been applied to measure self-broadened S-branch N2–N2 Raman linewidths in the temperature range 294–1466 K. The coherence decays were detected dire...
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Article
Influence of soot particle aggregation on time-resolved laser-induced incandescence signals
Laser-induced incandescence (LII) is a versatile technique for quantitative soot measurements in flames and exhausts. When used for particle sizing, the time-resolved signals are analysed as these will show a ...
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Article
On the influence of bimodal size distributions in particle sizing using laser-induced incandescence
Time-resolved laser-induced incandescence (LII) is a technique for in-situ soot particle size distribution measurements with the limitation that the distribution function has to be assumed (often monodisperse ...
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Article
Influence of spatial laser energy distribution on evaluated soot particle sizes using two-colour laser-induced incandescence in a flat premixed ethylene/air flame
Time-resolved laser-induced incandescence (LII) has been developed rapidly during the last decade as a useful non-intrusive technique for particle size determination. Still several parameters should be investi...
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Article
Soot volume fraction measurements in aero-engine exhausts using extinction-calibrated backward laser-induced incandescence
Control and reduction of soot particle emissions from aeronautic turbines requires a monitoring system suitable for quantification of these emissions. Currently, such emissions are estimated using the techniqu...
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Article
On the dependence of the laser-induced incandescence (LII) signal on soot volume fraction for variations in particle size
“The laser-induced incandescence (LII) signal is proportional to soot volume fraction” is an often used statement in scientific papers, and it has – within experimental uncertainties – been validated in compar...
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Article
Modeling laser-induced incandescence of soot: a summary and comparison of LII models
We have performed a comparison of ten models that predict the temporal behavior of laser-induced incandescence (LII) of soot. In this paper we present a summary of the models and comparisons of calculated temp...
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Article
Experimental and theoretical comparison of spatially resolved laser-induced incandescence (LII) signals of soot in backward and right-angle configuration
In-situ measurements of soot volume fraction in the exhausts of jet engines can be carried out using the laser-induced incandescence (LII) technique in backward configuration, in which the signal is detected i...
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Article
Characteristics of laser-induced incandescence from soot in studies of a time-dependent heat- and mass-transfer model
The temporal behavior of the laser-induced incandescence (LII) signal is often used for soot-particle sizing, which is possible because the cooling behavior of a laser-heated particle is dependent on the parti...
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Article
Soot visualisation by use of laser-induced soot vapourisation in combination with polarisation spectroscopy
A novel approach to the visualisation of soot is presented. It relies on a combination of laser-induced soot vapourisation and consecutive polarisation spectroscopy. Upon soot vapourisation, molecular fragment...
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Article
Dual-broadband rotational CARS modelling of nitrogen at pressures up to 9 MPa. I. Inter-branch interference effect
An improved model for pure rotational coherent anti-Stokes Raman scattering (CARS) has been developed for the dual-broadband approach. This model takes into account the fact that coherent anti-Stokes as well a...
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Article
Dual-broadband rotational CARS modelling of nitrogen at pressures up to 9 MPa. II. Rotational Raman line widths
Rotational coherent anti-Stokes Raman spectroscopy (CARS) is a well-established spectroscopic technique for thermometry at pre-combustion temperatures and atmospheric pressure. However, at pressures of several...
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Article
Quantitative three-dimensional imaging of soot volume fraction in turbulent non-premixed flames
A three-dimensional (3-D) imaging system for studies of reactive and non-reactive flows is described. It can be used to reveal the topology of turbulent structures and to extract 3-D quantities, such as conce...
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Article
Laser-induced incandescence for soot particle size and volume fraction measurements using on-line extinction calibration
A novel technique for two-dimensional measurements of soot volume fraction and particle size has been developed. It is based on a combined measurement of extinction and laser-induced incandescence using Nd:YAG...
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Article
Temperature and concentration measurements in acetylene-nitrogen mixtures in the range 300–600 K using dual-broadband rotational CARS
Pure rotational coherent anti-Stokes Raman scattering (CARS) experiments have been performed in acetylene for temperatures ranging from 294 to 582 K, and in mixtures of acetylene and nitrogen in the mole fract...
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Article
Two-dimensional imaging of glyoxal (C2H2O2) in acetylene flames using laser-induced fluorescence
H2O2). Laser-induced fluorescence spectra from glyoxal vapor using the same excitation wavelength of 428 nm showed the same strongest lines as the signal from the flame. Glyoxal was visualized in two different mo...
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Article
Oxygen concentration and temperature measurements in N2–O2 mixtures using rotational coherent anti-Stokes Raman spectroscopy
The accuracy and precision of oxygen concentration and temperature measured by dual-broadband rotational Coherent Anti-Stokes Raman Spectroscopy (CARS) were investigated in nitrogen-oxygen mixtures at atmosphe...
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Article
Soot-visualization strategies using laser techniques
Strategies for spatially resolved soot volume-fraction measurements have been investigated in sooting laboratory flames with known soot characteristics. Two techniques were compared: Laser-Induced Fluorescence...
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Article
Carbon atom fluorescence and C2 emission detected in fuel-rich flames using a UV laser
Laser-induced fluorescence from carbon atoms, excited at the two-photon resonances around 280 nm, has been detected in fuel-rich hydrocarbon flames together with Swan band emission from the C2 radical, which was ...