Aviation – Environmental Threats Simplified methodology of NOx and CO emissions estimation
Based on the available information and authors self - assessments, this article presents turbine engine exhaust gases effect on the environment, especially near to the aircraft during their engines idle and take-offs settings. The authors would like to draw attention of the aviation professionals to the fact that amount of exhaust from the turbine engine is so significant that may adversely change the ambient air near to the aircraft. Consequently increased level of carbon monoxide (CO), unburned hydrocarbons (UHC) during engine start–up and idle can be a threat to the ramp staff health. Also high emission level of the nitrogen oxides (NOx), during take-off, climb, cruise and decent is not indifferent for the environment around airport space as well as ionosphere . The paper gives an example of CO and NOx emission estimation based on ICAO Engine Emission Data Bank. Also provides calculation results of aircraft CO2, CO and NOx effusion using fuel consumption data taken from aircraft Flight Data Recorder (FDR) in the so–called landing and take-off cycle (LTO) and during remaining flight phases of various aircraft types. LTO cycle considered in this paper contains actual values of aircraft fuel consumption and duration of the airplane manoeuvres. Fig. 1 shows difference between fuel consumption of “model” and overhauled engines, when Fig.2 presents emissions estimation for “model” engine. Fig. 1Fuel consumption of: a-ICAO Emission Data Bank Engine; Fig. 2CO and NOx emissions for ICAO Data Bank Engine. b, c- test-cell results of overhauled engines It is cliché that engines during exploitation are deteriorating and have different characteristics hence such factors has to be taken into consideration in emission calculations and each aircraft, even of the same type, has to be considered individually. Fig. 3 presents how emission of NOx differs between overhauled and ideal engine on high power settings. Approximate value of NOx emission for repaired engines has been calculated using as a standard equations describing curves of “model” engine (Fig.2). Fig. 3NOx emission estimation on high power settings of: a-ICAO Emission Data Bank Engine; b, c- test-cell results of overhauled engines Fig. 4 shows quantity of NOx and CO emissions estimations for all flight phases of long haul aircraft. During same flight (Fig. 4) aircraft has emitted 150 000 kg CO2. For short and medium range flights “share” of cruise phase in total flight duration is smaller in favour of LTO cycle. Calculated on the engine characteristics basis the mass flow rate of exhaust gases, and knowledge of the aircraft real LTO cycle duration allow to estimate the amount of CO2, CO and UHC “left" at the airport space. The final answer to questions about threats to the ramp staff can be obtained after a detailed study of the pollutants concentration distribution zones (a task for us - engineers) and determine the safe limits of these gases for human (a task for medical services). High altitude emissions especially NOx and CO2, their influence on ionosphere requires more studies of climate experts. For now we are trying to estimate more precisely volume of pollutants.