Multi-directional 3D flame chemiluminescence tomography based on lens imaging

Area of Science:

• Combustion diagnostics
• Optical engineering
• Tomographic imaging

Background:

• Flame chemiluminescence tomography (FCT) enables 3D flame measurements.
• Traditional FCT uses parallel projection models, which are inaccurate for lens-based imaging systems.
• Lens light collection characteristics, especially at small F-numbers, necessitate a revised tomographic approach.

Purpose of the Study:

• To develop a novel tomographic theory for multi-directional FCT systems incorporating lens effects.
• To improve the accuracy of 3D flame geometry and species concentration measurements.
• To establish a more appropriate projection model for practical FCT optical setups.

Main Methods:

• A modified camera calibration method was developed to determine precise camera spatial locations and intrinsic parameters.
• A new 3D projection model, based on lens imaging theory, was established.
• The new model was integrated into the multiplicative algebraic reconstruction technique (MART) for tomographic reconstruction.

Main Results:

• The novel tomographic theory and 3D projection model were successfully demonstrated using a 12-camera system.
• Accurate reconstruction of the emission field of a propane flame was achieved.
• The method resolved both spatial and temporal characteristics of the flame emission.

Conclusions:

• The developed FCT approach accurately reconstructs 3D flame structures by accounting for lens light collection effects.
• This novel theory provides a more appropriate model for FCT systems, enhancing diagnostic capabilities.
• The improved method offers precise, spatially and temporally resolved measurements for flame analysis.