With the support of the MAHEPA project, the Institute for Energy Conversion and storage at the University of Ulm was able to build up an engine test bench for the Rotax 915 iS engine, in order to perform gaseous emission analysis.
The ‘heart of the testbench’ is the emission measurement device in which the composition of the exhaust gas (CO2, CO, NOX, CxHy, O2, and SO2) are measured. Using this test bench, different fuels are used to power the engine, with specific set points to test, in order to keep a comparable basis. For this project, we are comparing AvGas, regular gasoline, gasoline with 10 % ethanol, and 20 % ethanol. Did you know that, although ethanol has lower energy density than regular gasoline, the completeness of the combustion process increases with increasing ethanol content? This is why it is important to look so detailed at the emissions based on fuel and engine operational point.
As the data has been collected, we are analyzing the outcome in terms of how this affects the future of flying. With this detailed data on exhaust emissions from aircraft engines, what can we, as researchers and aircraft manufacturers, do with the gained knowledge? Using both information about the varying fuels and the optimal operating points of the engine, we obtain knowledge of the gaseous emissions produced depending on the conditions. With the developed methods from the test bench research, the combustion engine of the ICE-hybrid can be operated with optimal exhaust emissions for the given flight phase. The emission optimized ICE-hybrid can help to reach the goals of Flightpath2050.