SIGIS HR: A system for Measurement of Aircraft Exhaust Gas under Normal Operating Conditions of an Airport

摘要

To gather information about the impact on the environment caused by airport operations, knowledge about the amount of gases such as CO or NO_x emitted by aircraft engines on the ground is important. In order to avoid influences on airport operations an analysis system for this application has to enable measurements of the hot jet engine exhaust gas from a distance. The infrared radiation emitted by the hot gas can be analysed by Fourier-transform infrared spectroscopy to determine the composition of the gas. To fulfil this task, a new version of the scanning infrared gas imaging system (SIGIS HR), using relatively high spectral resolution (0.2 cm~(-1)), has been developed. The period of time for measurements on the engine exhaust gas of an aircraft on the ground is short during normal airport operations. Hence the remote sensing system has to be aligned to the exhaust gas plume quickly. For this reason the system is equipped with a scanning mirror actuated by stepper motors in order to allow fast changes of the line of sight. An infrared camera combined with a DSP-system enables automatic alignment of the system to the hot exhaust gas and tracking of a moving engine via online analysis of the infrared image. Additionally fast scans with low spectral resolution of the area around the engine-outlet can be performed. On the basis of the low resolution data the optimal direction for the exhaust gas measurement can be found using several automatic evaluation- and positioning-algorithms. After the SIGIS HR-system has been positioned correctly it is operated in high-resolution-mode in order to quantify the target compounds.