Per-Erik Bengtsson

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Measurements of soot properties by means of laser-induced incandescence (LII) and combined scattering-extinction were performed in well-characterized premixed ethylene-air flames. In particular, the possibility of using LII as a tool for quantitative particle sizing was investigated. Particle sizes were evaluated from the temporal decay of the LII signal(More)
Formaldehyde (CH2O) is an important intermediate species in combustion processes and it can through laser-induced fluorescence measurements be used for instantaneous flame front detection. The present study has focussed on the use of the third harmonic of a Nd:YAG laser at 355 nm as excitation wavelength for formaldehyde, and different dimethyl ether(More)
A detailed experimental investigation has been made of the pyrolysis--the first step in biomass combustion--of single birchwood particles. In addition to mass spectrometric and gravimetric analysis, the pyrolysis volatiles were characterized by different optical techniques. Absorption measurements showed a nearly featureless absorption in the ultraviolet(More)
A dual-pump, dual-broadband coherent anti-Stokes Raman scattering system for simultaneous measurements of temperature and concentrations of N2, O2, and CO2 in reacting flows is demonstrated. In this system pure rotational transitions of N2-O2 and rovibrational transitions of N2-CO2 are probed simultaneously with two narrowband pump beams, a broadband pump(More)
Different rotational CARS techniques have been evaluated in terms of single-shot temperature accuracy and signal intensity in room temperature nitrogen and in flames. The different techniques include both dual broadband techniques, using one or two broadband dye lasers, and conventional rotational CARS with different dye lasers. These techniques are also(More)
The potential of measuring temperature and multiple species concentrations (N2, O2, CO) by use of combined vibrational coherent anti-Stokes Raman spectroscopy (CARS) and pure rotational CARS has been investigated. This was achieved with only one Nd:YAG laser and one dye laser together with a single spectrograph and CCD camera. From measurements in premixed(More)
Soot particles can be formed in hydrocarbon flames as a result of an inefficient combustion process. The particles are near-spherical, and at later stages in the soot growth process, they form chainlike sparse aggregates. When applying optical diagnostic methods, this aggregation influences the evaluation of soot properties based on assumptions of isolated(More)
Experiments were performed in the temperature range of 294-1143 K in pure CO(2) using high-resolution rotational coherent anti-Stokes Raman spectroscopy (CARS), in the dual-broadband approach. Experimental single-shot spectra were recorded with high spectral resolution using a single-mode Nd:YAG laser and a relay imaging lens system on the exit of a 1 m(More)
It is well known that spectroscopic measurements suffer from an interference known as stray light, causing spectral distortion that reduces measurement accuracy. In severe situations, stray light may even obscure the existence of spectral lines. Here a novel general method is presented, named Periodic Shadowing, that enables effective stray light(More)