Flame monitoring of a model swirl injector using 1D tunable diode laser absorption spectroscopy tomography

Abstract

Distributions of temperature and H 2 O concentration in a swirling flame are critical to evaluate the performance of a gas turbine combustor. In this paper, 1D tunable diode laser absorption spectroscopy tomography (1D-TDLAST) was introduced to monitor swirling flames generated from a model swirl injector by simultaneously reconstructing the rotationally symmetric distributions of temperature and H 2 O concentration. The optical system was sufficiently simplified by introducing only one fan-beam illumination and a linear detector array of 12 equally-spaced photodetectors. The fan-beam illumination penetrated a cross section of interest in the swirling flame and the transmitted intensities were detected by the detector array. With the transmitted intensities in hand, projections were extracted and employed by a 1D tomographic algorithm to reconstruct the distributions of temperature and H 2 O concentration. The route of the precessing vortex core generated in the swirling flame can be easily inferred from the reconstructed profiles of temperature and H 2 O concentration at different heights above the nozzle of the swirl injector.

Toward Customized Spatial Resolution in TDLAS Tomography

“…In industrial applications, the requirements placed on the spatial resolution of a tomographic image depend on the size of the target combustion field and the size of the smallest feature to be detected. For instance, process control in large-size coal-fired/biomass boilers [18,19] and thermal power plants [20] requires centimeter-level spatial resolution in the tomographic image, while combustion diagnostics in automotive engines [9,21] and swirl combustors [17,22] for millimeter-level spatial resolution. Visualization of the mixing process has been previously demonstrated for both the liquid and vapor phases of fuel injected in the chamber of Spark Ignition (SI) and Compression Ignition (CI) engines [9,21], however the spatial resolution was insufficient to tomographically resolve the fuel spray pattern.…”

Online Cross-Sectional Monitoring of a Swirling Flame Using TDLAS Tomography

“…In addition, the temperature distributions in the averaged images are rotationally symmetric. That is to say, the mean temperature values extracted from the same radius of the ROI are identical [34], [39], [40]. Here, mean temperature values on the positive x-axis in Fig.…”

Nanoparticles in analytical laser and plasma spectroscopy – a review of recent developments in methodology and applications

“…100 Even though absorption-based techniques provide line of sight information, by employing fan-shaped laser illumination and multiple detectors, temperature and concentration distributions can be reconstructed using a 1D tomographic algorithm. 103 Another method enabling the online monitoring of the ame temperature and the concentration of the intermediate species is laser-induced uorescence (LIF). LIF methods are usually distinguished by the species the measurements are based on, such as NO or OH for temperature, and various other species (e.g., Fe, CH 2 O, CH, OH, SiO, FeO, In, AlO, TiO) for intermediate concentration determination.…”