Extending Sensing Range by Physics Constraints in Multiband-Multiline Absorption Spectroscopy for Flame Measurement

Area of Science:

• Combustion diagnostics
• Laser spectroscopy
• Optical sensing

Background:

• Flame measurements are crucial for understanding combustion processes.
• Traditional tunable diode laser absorption spectroscopy (TDLAS) has limitations in sensing range and accuracy for complex flames.

Purpose of the Study:

• To develop an advanced TDLAS technique for extended sensing range in flame measurements.
• To improve the accuracy and robustness of TDLAS by incorporating physical constraints.

Main Methods:

• Utilized physics constraints on gas conditions and spectroscopic parameters.
• Analyzed spectra from multiple bands (4029-4031 cm⁻¹ and 7185-7186 cm⁻¹) using a custom detection function and contribution filtering.
• Determined 24 major spectral lines for analysis.

Main Results:

• Demonstrated high accuracy and strong robustness to noise in numerical tests.
• Achieved a significantly wider sensing range compared to conventional TDLAS.
• Showcased good compatibility with tomographic reconstruction.

Conclusions:

• The proposed TDLAS technique offers a powerful tool for complex combustion detection.
• Advanced laser sources with broad spectra can be effectively utilized with this method.
• This approach enhances the capability of laser-based combustion diagnostics.