Width-increased dual-pump enhanced coherent anti-Stokes Raman spectroscopy

Area of Science:

• Combustion science
• Spectroscopy
• Chemical kinetics

Background:

• Supersonic combustion requires precise measurements of temperature and species.
• Existing techniques may struggle with the complex chemical environments and high speeds involved.

Purpose of the Study:

• To introduce and validate Width-increased dual-pump enhanced coherent anti-Stokes Raman spectroscopy (WIDECARS) for supersonic combustion analysis.
• To demonstrate WIDECARS' capability in measuring multiple species and temperature simultaneously.

Main Methods:

• Utilizing WIDECARS, a dual-pump CARS technique with an increased spectral width.
• Targeting specific rotational Raman transitions of hydrogen (H(2) S(3) and H(2) S(4)) for diagnostics.
• Analyzing supersonic flows fueled by hydrogen and hydrogen/ethylene mixtures.

Main Results:

• Simultaneous measurement of temperature and mole fractions for N(2), O(2), H(2), C(2)H(4), CO, and CO(2) was achieved.
• WIDECARS demonstrated effectiveness in supersonic combustion environments.
• The technique successfully measured conditions in pure hydrogen fuel at room temperature.

Conclusions:

• WIDECARS is a viable technique for comprehensive diagnostics in supersonic combustion.
• It provides simultaneous temperature and major species concentration data, excluding water.
• The method is applicable to hydrogen and hydrogen/ethylene fueled supersonic flows.