Three-color high-sensitivity thermometry using infrared laser absorption spectroscopy of NO

A novel three-color high-sensitivity thermometry method is proposed, providing more accurate temperature measurements for nitrogen-containing fuel reactive flows. This method determines temperature by simultaneously sweeping three absorption peaks of NO. A relationship between absorbance and temperature was established with parameters determined from shock tube experiments from 1100 to 2200 K. To evaluate its performance, six sets of NO absorption spectra data at various temperatures were collected. The results demonstrate that the three-color thermometry achieves an average absolute error of 7 K, significantly lower than the two-color thermometry’s average absolute errors of 16 and 20 K. This three-color thermometry methods offers higher sensitivity and accuracy, making it a practical solution for measuring temperatures during the combustion of nitrogen-containing fuels.