Broadband supercontinuum laser absorption spectrometer for multiparameter gas phase combustion diagnostics

Area of Science:

• Spectroscopy
• Combustion Diagnostics
• Laser Technology

Background:

• Combustion diagnostics require precise measurements of species concentrations.
• High-pressure and high-temperature environments pose challenges for traditional spectroscopic methods.
• Supercontinuum broadband absorption spectroscopy (SCLAS) offers broad spectral coverage suitable for harsh conditions.

Purpose of the Study:

• To develop and validate a broadband absorption spectrometer for measuring methane mole fractions in flames.
• To assess the applicability of SCLAS in combustion environments.
• To demonstrate the capability of SCLAS for in-flame measurements with short absorption paths.

Main Methods:

• Utilized a pulsed supercontinuum laser and dispersion compensating fiber.
• Employed a single-pass absorption path on a Wolfhard-Parker burner.
• Applied a tunable diode laser absorption spectroscopy (TDLAS) fitting algorithm to SCLAS data.

Main Results:

• Achieved spectral resolutions up to 0.152 cm⁻¹ and spectral coverage over 110 cm⁻¹.
• Successfully measured absolute methane mole fractions with resolutions of 3%(Vol.) (1210 ppm·m).
• Demonstrated the suitability of SCLAS for combustion diagnostics with a 41 mm absorption path.

Conclusions:

• SCLAS is a viable technique for in-flame combustion diagnostics, particularly in harsh environments.
• The validated TDLAS algorithm is effective for analyzing SCLAS data.
• This method shows potential for extension to other species and combustion parameters.