Observation of NO and NO2 in the young plume of an aircraft jet engine

For the first time the emission indices of NO and NO2 were measured simultaneously in-flight by a non-intrusive spectrometric measurement setup. Moreover the method described here is capable of determining the (static) temperature of the exhaust gas and emission indices for H2O and CO at the same time with a precision of 1-4%. After a very brief description of the experimental setup, results of measurements are shown. They reveal mean emission indices for EI(NO2) of 1 g/kg and 3-5 g/kg for EI(NO) (estimated accuracy: 20-25%). The ratio of concentrations [NO2]/[NOx] of 12-22% is by a factor of approximately two higher than most values cited for other engines, Based on the bulk mean properties of the plume it is shown that the temperature determination is accurate to several Kelvin.