Exhaust Emissions from In-Use General Aviation Aircraft (2016) / Chapter Skim
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Pages 45-61
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Other Parameters Affecting Emissions 45 engine exhaust temperatures. To combat this problem, dibromoethane is added to 100 LL.
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46 Exhaust Emissions from In-Use General Aviation Aircraft approximately 80% of HC exhaust consists of the same compounds present in the fuel in nearly the same distribution. The remaining 20% of the HC exhaust consists of decomposed fuel in the form of small hydrocarbons such as acetylene and partially oxidized material like formaldehyde.
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Other Parameters Affecting Emissions 47 regulations, and any likely future regulations with a smaller cutoff (for particles smaller than 1 or 0.1 µm, for instance)
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48 Exhaust Emissions from In-Use General Aviation Aircraft EEPS measures total particle number, which ensures that black carbon particles are weighted to a larger size due to coating by volatiles. Given that the uncertainty in the EEPS counting efficiency increases at larger particle size, and the larger particles contribute most to mass, comparison to the MAAP is, at best, approximate.
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Other Parameters Affecting Emissions 49 For almost all of the engines in the measurement database from this project the emitted particles were observed to have a geometric mean diameter (GMD) that is small (<20 nm)
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50 Exhaust Emissions from In-Use General Aviation Aircraft because the combustion process was the same for each stroke of the piston engine, unlike a gas turbine where the fuel air mixing is modulated vs. engine power.
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Other Parameters Affecting Emissions 51 Figure 5-14. Particle size distributions for the TPE331-6-252B turboprop engine.
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52 Exhaust Emissions from In-Use General Aviation Aircraft Figure 5-15. Emission indices of nvPM in number and mass for the CF34 turbofan engine.
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53 C H A P T E R 6 In this report, emission indices are listed for 47 full engine tests. A thorough analysis of trends and variability in these EIs is presented, with emphasis on the statistical comparison of the research team's results with existing data.
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54 Exhaust Emissions from In-Use General Aviation Aircraft b. The assumption underlying this goal of substitution is that one engine type yields one set of well-defined emission indices.
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Conclusions 55 • Researching real airport operations to determine times-in-mode that are more representative of true GA operations. Throughout this research, the default values for time spent in taxi (taxi and idle are often clumped together)
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56 A P P E N D I X A The prioritized list of engines below was used in the planning stages of the research to prioritize the engines measured. The rank of the aircraft engine is based on the FAA registry of the national GA fleet for piston engines and turbofan engines in 2014.
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57 A P P E N D I X B The test matrix reproduced here was used by the cockpit observer to direct the engine tests and note all relevant conditions. Test Matrix
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58 Exhaust Emissions from In-Use General Aviation Aircraft Date Time (Local) Pilot Time (UTC)
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Test Matrix 59 Approach Idle Climb Out Propellor RPM Throttle/Manifold Pressure or % Engine RPM Fuel Mixture % of full rich Oil Temp Engine Cyl. Head T/ EGT Oil Pressure Fuel Flow Air/Fuel Ratio Approach Idle Take off Propellor RPM Throttle/Manifold Pressure or % Engine RPM Fuel Mixture % of full rich Oil Temp Engine Cyl.
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60 The ICAO maintains a database of turbofan engine emission indices, with the operational states defined based on a percentage of available thrust. The Swiss Federal Office of Civil Aviation (FOCA)
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61 Method for Calculating Emission Ratios Emission ratios are the first step in calculating emission indices from time series data. This appendix details methods of determining emission ratios.
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