Spectroscopic remote sensing of aircraft exhausts at airports

Emission indices of aircraft engine exhausts must be known to calculate precisely the emissions of aircraft on airports during different operational scenarios. FTIR emission spectroscopy of exhausts was developed further as a remote sensing multi- component analysis method. Measurements at different aircraft engines were used to develop basically and optimize the measurement and analysis procedure during run up tests at ground level. The measured main engines are GE90-85B and RB211 as well as APUs of the B777 and B747. A temperature stabilized spectrometer in a van collected good quality spectra at 0.2 cm -1 resolution. The FTIR instrument was aligned to the engine nozzle exit with a two axis movable entrance mirror. Setting up the system needs about 10 to 20 minutes, if all systems are running on standby. Total measurement times at one thrust level should be around 5 minutes to obtain reliable results. The FTIR engine measurement results for CO 2 , CO, and NO have been proven to be in agreement with intrusive measurement data collected during engine runs in a test rig. The deviations were generally in the order of +/- 30 percent, i.e. comparable to the day-to-day variations of the engine emissions.