Hydrogen CARS thermometry in a high-pressure H2-air flame. Test of H2 temperature accuracy and influence of line width by comparison with N2 CARS as reference

This work describes a further step towards the determination of the temperature accuracy of H2 Q-branch CARS (Coherent Anti-Stokes Raman Scattering) at high pressure with regard to the influence of the H2 line widths. In laminar steady H2/air flames in the pressure range 1–15 bar and at fuel-rich conditions with stoichiometries between two and four, quasi-simultaneous temperature measurements were performed with H2 and N2 CARS. The temperature values deduced from H2 CARS are in good agreement with the reference temperature from N2 CARS. The influence of different line-width contributions on the accuracy of H2 Q-branch thermometry was investigated in detail.