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3D Front Tomography Reconstruction of Swirl Flame by Ultraviolet Multi-Camera Imaging

  

  • Received:2022-11-29 Revised:2023-01-13 Online:2023-02-01 Published:2023-02-01

Abstract: The front of swirl flame can be used to characterize the flame macrostructure and combustion stability, making the transi-ent 3D structure measurement extremely important for research on the swirl combustion mechanism and swirl burner optimization. In this work, a measuring approach for transient 3D front of swirl combustion flame by ultraviolet multi-camera imaging is proposed. In order to acquire transient chemiluminescence information at a cheap cost with high pre-cision, a computed tomography of chemiluminescence system (CTC) based on an ultraviolet multi-camera array is built. Additionally, the simultaneous algebraic reconstruction technique (SART) is improved using a pre-recognition method for non-intensity voxels identification by ray tracing, resulting in less computational load and reconstruction artifacts. Numer-ical simulation experiments are executed to confirm the precision and noise immunity of the reconstruction algorithm. A methane-air premixed swirl combustion experimental rig is built finally, then the calibration of the ultraviolet multi-camera imaging system and low-swirl flame front experiments are carried out. The results show that the inverse projection's ac-curacy exceeds 0.97 while the calculation is reduced by 59.6%. Secondly, the low swirl flame expands at the nozzle exit under stable combustion conditions and displays a vortex bowl-shaped structure. In addition, the flame pushing height rises slightly as the equivalent ratio grows, and the flame volume gradually increases as well, which enhances combus-tion stability.

Key words: Ultraviolet imaging, Swirl combustion flame, Front structure, 3-Dimensional tomographic reconstruction, Chemiluminescence

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