Laser Absorption Spectroscopy Tomography of Dynamic Flames

Dynamic temperature imaging is essential for characterising the thermophysical performance of the combustion process. It is also of great importance for evaluation of the next-generation sustainable fuels in terms of combustion instability and efficiency. Using Laser Absorption Spectroscopy Tomography (LAST), Dr Chang Liu and his research group have developed a robust 32-beam optical sensor, a high-speed multi-channel data acquisition system, and imaging algorithms to reconstruct the cross-sectional temperature distributions of dynamic flames at 1 kilo frames per second (fps). A video indicating the dynamic flames during a 4-seconds combustion process is recorded at 30 fps. The temperature distributions at a cross section of the flames are reconstructed at 1k fps with a 10-time slower motion of the reconstruction shown in the video. The video clearly shows strong consistency between the real flames and the reconstructions. Flame 1 vibrates with temperature firstly decreased and then gradually increased, while flame 2 gives periodical vibration. This work is a lab-scale experiment of the EPSRC Platform Grant “In-situ Chemical Measurement and Imaging Diagnostics for Energy Process Engineering (CIDER)” (EP/P001661/1).