Measurement of engine exhaust plume temperature and concentration distributions with tomographic absorption spectroscopy and learning-based absorbance recovery

• Published in: Fuel (Guildford) 2024-12, Vol.377, p.132775, Article 132775
• Main Authors: Wang, Ruifeng, Yu, Pengfei, Huang, Tianxu, Cao, Yuan, Mei, Jiaoxu, Wang, Guishi, Gao, Xiaoming, Liu, Kun
• Format: Article
• Language: English
• Subjects: Absorbance recovery; Combustion diagnostics; Concentration distribution; Temperature distribution; Tomographic absorption spectroscopy
• ISSN: 0016-2361
• DOI: 10.1016/j.fuel.2024.132775

•A tomographic imaging system for gas temperature and concentration is developed.•Single path measurement accuracy is improved by learning-based absorbance recovery.•Exhaust temperature and H2O distributions on a small turbojet engine is measured.•Microsecond scale variations in temperature and H2O concentration is captured.•Reconstructed center temperature agrees with thermocouple measurements. Measuring the spatial distribution of temperature and species concentration is important to the thermodynamic analysis and validation of modern combustion systems. In this work, we developed a measurement method based on tomographic absorption spectroscopy (TAS) for the quantitative measurement of two-dimensional distributions of gas temperature and concentration. A learning-based absorbance recovery method was proposed and incorporated into TAS to address the baseline error induced distortion of absorbance and improve the accuracy of single path measurement. The developed TAS system, consisting of 12 laser beams, was demonstrated on a diesel fueled small turbojet engine. Temperature and H2O concentration distributions of the exhaust plume were measured with laser wavelength scan rates of 20 kHz. Temperature variations in microsecond-scale were captured and the time-averaged center temperature agreed well with thermocouple measurements. The developed TAS method demonstrates the feasibility of real-time and accurate tomographic imaging for practical combustion flows, which could be effectively applied for widespread combustion diagnostics.