Determination of exhaust composition in turbine test beds by FTIR emission spectrometry

A modified mid-size low by-pass aero-engine running on a sea level test bed was used for measurements with non-intrusive demonstrator systems and currently used gas sampling analysis techniques. A novel open-path White mirror system was developed and installed in the test bed to enhance the sensitivity of non-intrusive FTIR spectrometry. A comparison was made of the different measurement techniques at several engine thrust levels i.e. gas concentrations. This included the emission and absorption mode of the FTIR-spectrometers with the multi-path reflection compartment as well as the single emission mode. A new calibration procedure with a hot cell filled with CO (temperatures 300 to 750 K) was developed and used to calibrate the FTIR instruments. Retrieval results from FTIR measurements were obtained by using a rectangular and Gaussian distribution profile of temperature and gas concentrations in the plume. The FTIR measurement results for CO2, CO, and NO have been proven to be in agreement with the intrusive data. The deviations were generally in the order of plus or minus 30%, i.e. comparable to the day-to-day variations of the engine emissions. NO2 could be detected in the absorption mode only.© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.