In the current test campaign together with the University of the Bundeswehr Munich (UniBWm), a synthetic kerosene produced using the Fischer Tropsch process (FT-SPK) is being investigated. In addition to the currently permitted blending ratio of 50% FT-SPK to conventional Jet A-1, 100% pure FT-SPK is also being used. In the tests, the FT-SPK is burned in an Allison 250 C20B helicopter gas turbine. The particle and gas phase of the exhaust gas is sampled directly in the exhaust pipe of the engine using UniBWm's emission measurement technology. In addition to the typical gaseous emissions such as CO2, CO, NOx and unburned hydrocarbons, the tests also measure the atmospheric aging of the exhaust gases using an oxidation flow reactor. The aim is to determine which secondary organic aerosols are formed in the atmosphere over time - for both kerosene and FT-SPK.
To better understand the differences in the formation of soot particles between Jet A-1 and FT-SPK, an online mass spectrometer will also be used in this year's tests to measure the proportion of polycyclic aromatic hydrocarbons (PAHs) in particular, which are regarded as soot precursors according to current theories.
This year's test campaign with FT-SPK is already the third of its kind, with the first focusing exclusively on Jet A-1 and the second on the sustainable aviation fuel HEFA-SPK (results on HEFA-SPK published at this year's ASME Turbo Expo 2024).