A dual-gas sensor system is developed for CO and CO_2 detection using a single broadband light source, pyroelectric detectors and time-division multiplexing(TDM) technique. A stepper motor based rotating system and a ...A dual-gas sensor system is developed for CO and CO_2 detection using a single broadband light source, pyroelectric detectors and time-division multiplexing(TDM) technique. A stepper motor based rotating system and a single-reflection spherical optical mirror are designed and adopted for realizing and enhancing dual-gas detection. Detailed measurements under static detection mode(without rotation) and dynamic mode(with rotation) are performed to study the performance of the sensor system for the two gas samples. The detection period is 7.9 s in one round of detection by scanning the two detectors. Based on an Allan deviation analysis, the 1σ detection limits under static operation are 3.0 parts per million(ppm) in volume and 2.6 ppm for CO and CO_2, respectively, and those under dynamic operation are 9.4 ppm and 10.8 ppm for CO and CO_2, respectively. The reported sensor has potential applications in various fields requiring CO and CO_2 detection such as in the coal mine.展开更多
For tomographic reconstruction in combustion diagnostics,it is usually necessary to solve a rank-deficient problem,where the number of non-linear dependent equations is smaller than the number of unknowns.In some reco...For tomographic reconstruction in combustion diagnostics,it is usually necessary to solve a rank-deficient problem,where the number of non-linear dependent equations is smaller than the number of unknowns.In some reconstructions,there are grids without rays passing through.This produces artifacts during the reconstruction.In this paper,the weight of the regulation equation is modified with the number of the rays crossing the grid cells.The effect of the neighboring grid values as well as the number of rays crossing the grid cells is considered in the new regulation method.Numerical simulation results show that the new regulation method suppresses the reconstruction error of the no rays crossing grid and successfully restrains the corner distortion in four projection angles.The effects of the weight coefficient and the smoothing factor on the reconstruction are examined through a numerical study.Finally,a combustion experiment demonstrates that the new regulation method can significantly reduce the reconstructed error,especially for the nonray crossing condition,and the results are compared with thermocouple measurements and reconstructions without modified regulation.展开更多
This paper describes a self-designed fiber-coupled tomography system and its application in combustion diagnostics. The tomographic technique, which combines tunable diode laser spectroscopy and algebraic reconstructi...This paper describes a self-designed fiber-coupled tomography system and its application in combustion diagnostics. The tomographic technique, which combines tunable diode laser spectroscopy and algebraic reconstruction technique, enables the simultaneous reconstruction of temperature and gas concentration with both spatial and temporal resolutions. The system measures a maximum diameter of 35 cm in a circular area with a minimum spatial resolution of 1 mm×1 mm and temporal response of up to 1 kHz. Simulations validate the effects of the beam arrangement and discrete grid on reconstruction accuracy, and give the optimal beam arrangements. Experiments are made to demonstrate the tomography method, and systems are constructed in laboratory and on engineering test benches.展开更多
基金supported by the National Key R&D Program of China(Nos.2016YFD0700101 and 2016YFC0303902)the National Natural Science Foundation of China(Nos.61775079,61627823 and 61307124)+3 种基金the Science and Technology Planning Project of Guangdong Province,China(No.2017A020216011)the Science and Technology Development Program of Jilin Province,China(No.20140307014SF)the Industrial Innovation Program of Jilin Province,China(No.2017C027)Changchun Municipal Science and Technology Bureau,China(No.14KG022)
文摘A dual-gas sensor system is developed for CO and CO_2 detection using a single broadband light source, pyroelectric detectors and time-division multiplexing(TDM) technique. A stepper motor based rotating system and a single-reflection spherical optical mirror are designed and adopted for realizing and enhancing dual-gas detection. Detailed measurements under static detection mode(without rotation) and dynamic mode(with rotation) are performed to study the performance of the sensor system for the two gas samples. The detection period is 7.9 s in one round of detection by scanning the two detectors. Based on an Allan deviation analysis, the 1σ detection limits under static operation are 3.0 parts per million(ppm) in volume and 2.6 ppm for CO and CO_2, respectively, and those under dynamic operation are 9.4 ppm and 10.8 ppm for CO and CO_2, respectively. The reported sensor has potential applications in various fields requiring CO and CO_2 detection such as in the coal mine.
基金supported by the Beijing Natural Science Foundation(No.1194028)National Natural Science Foundation of China(No.61505263)State Key Laboratory of Laser Propulsion&Application Foundation(Nos.SKLLPA-03 and SKLLPA-15)。
文摘For tomographic reconstruction in combustion diagnostics,it is usually necessary to solve a rank-deficient problem,where the number of non-linear dependent equations is smaller than the number of unknowns.In some reconstructions,there are grids without rays passing through.This produces artifacts during the reconstruction.In this paper,the weight of the regulation equation is modified with the number of the rays crossing the grid cells.The effect of the neighboring grid values as well as the number of rays crossing the grid cells is considered in the new regulation method.Numerical simulation results show that the new regulation method suppresses the reconstruction error of the no rays crossing grid and successfully restrains the corner distortion in four projection angles.The effects of the weight coefficient and the smoothing factor on the reconstruction are examined through a numerical study.Finally,a combustion experiment demonstrates that the new regulation method can significantly reduce the reconstructed error,especially for the nonray crossing condition,and the results are compared with thermocouple measurements and reconstructions without modified regulation.
基金supported by the National Natural Science Foundation of China (No. 61505263)
文摘This paper describes a self-designed fiber-coupled tomography system and its application in combustion diagnostics. The tomographic technique, which combines tunable diode laser spectroscopy and algebraic reconstruction technique, enables the simultaneous reconstruction of temperature and gas concentration with both spatial and temporal resolutions. The system measures a maximum diameter of 35 cm in a circular area with a minimum spatial resolution of 1 mm×1 mm and temporal response of up to 1 kHz. Simulations validate the effects of the beam arrangement and discrete grid on reconstruction accuracy, and give the optimal beam arrangements. Experiments are made to demonstrate the tomography method, and systems are constructed in laboratory and on engineering test benches.
