Measurement of CO2 Concentration and Temperature in an Aero Engine Exhaust Plume Using Wavelength Modulation Spectroscopy

In this paper, the 2f/1f tunable diode laser wavelength modulation spectroscopy is used for the simultaneous measurement of concentration and temperature of CO2 in the exhaust plume of an aero engine. The suitability of the R48 spectral feature of CO2 at 1997.2 nm is discussed for this project and for further application of CO2 tomographic imaging on large-scale aero-engines. To ensure accurate recovery of gas parameters at the high exhaust temperatures, a full spectral characterization of the absorption feature is presented using a direct spectroscopy. The 2f/1f method is validated in the laboratory for controlled gas mixtures and temperatures to recover concentration and temperature. Good agreement with the actual temperature and concentration values is demonstrated. Finally, single path measurements are presented for an aero engine exhaust showing good correlation with the measured engine conditions.