title: Tunable diode laser absorption spectroscopy-based tomography system for on-line monitoring of two-dimensional distributions of temperature and H2O mole fraction.
abstract: To monitor two-dimensional (2D) distributions of temperature and H2O mole fraction, an on-line tomography system based on tunable diode laser absorption spectroscopy (TDLAS) was developed. To the best of the authors' knowledge, this is the first report on a multi-view TDLAS-based system for simultaneous tomographic visualization of temperature and H2O mole fraction in real time. The system consists of two distributed feedback (DFB) laser diodes, a tomographic sensor, electronic circuits, and a computer. The central frequencies of the two DFB laser diodes are at 7444.36 cm(-1) (1343.3 nm) and 7185.6 cm(-1) (1391.67 nm), respectively. The tomographic sensor is used to generate fan-beam illumination from five views and to produce 60 ray measurements. The electronic circuits not only provide stable temperature and precise current controlling signals for the laser diodes but also can accurately sample the transmitted laser intensities and extract integrated absorbances in real time. Finally, the integrated absorbances are transferred to the computer, in which the 2D distributions of temperature and H2O mole fraction are reconstructed by using a modified Landweber algorithm. In the experiments, the TDLAS-based tomography system was validated by using asymmetric premixed flames with fixed and time-varying equivalent ratios, respectively. The results demonstrate that the system is able to reconstruct the profiles of the 2D distributions of temperature and H2O mole fraction of the flame and effectively capture the dynamics of the combustion process, which exhibits good potential for flame monitoring and on-line combustion diagnosis.
authors.affiliation: School of Instrument Science and Opto-Electronic Engineering, Beihang University, Beijing 100191, China.
authors.forename: Lijun
authors.initials: L
authors.lastname: Xu
authors.affiliation: School of Instrument Science and Opto-Electronic Engineering, Beihang University, Beijing 100191, China.
authors.forename: Chang
authors.initials: C
authors.lastname: Liu
authors.affiliation: School of Instrument Science and Opto-Electronic Engineering, Beihang University, Beijing 100191, China.
authors.forename: Wenyang
authors.initials: W
authors.lastname: Jing
authors.affiliation: School of Instrument Science and Opto-Electronic Engineering, Beihang University, Beijing 100191, China.
authors.forename: Zhang
authors.initials: Z
authors.lastname: Cao
authors.affiliation: School of Energy and Power Engineering, Beihang University, Beijing 100191, China.
authors.forename: Xin
authors.initials: X
authors.lastname: Xue
authors.affiliation: School of Energy and Power Engineering, Beihang University, Beijing 100191, China.
authors.forename: Yuzhen
authors.initials: Y
authors.lastname: Lin