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Though nitrogen oxides (NOx ) emissions from aircraft make a relatively small contribution to the overall NOx emissions when compared to surface emissions, they constitute the only man-made pollutant at high altitude. Excessive NOx emissions might cause ozone depletion in the stratosphere and ozone increases in the troposphere, both topics of increasing environment concern in recent years. To tackle the problem of NOx emissions and their effects upon the environment, the spatial distribution of NOy (NOx + RN03) needs to be fully understood. The most significant source of NOx emissions is due to long range civil subsonic aircraft during their cruise phase. Detailed studies were performed for seven cases, including five single flight and two global scale scenarios, using the most widely used B747-400 aircraft which are powered by 4 three-shaft turbofan engines. Using models of aircraft performance, cruise phase NOx emissions are derived and employed as input to run a three-dimensional chemistry transport model. In order to achieve realistic results, all scenarios were carried out using a one-year period of simulation to study the transport and dispersion of NOy emitted from aircraft exhausts. For a better understanding of the atmospheric behaviour of NOy , two other cases were also carried out, a one-month simulation during both summer and winter situations. The results show that the upper troposphere may certainly be perturbed by aircraft NOx emissions at cruise altitude. The relative increase in NOx concentration is estimated to be of the order of 40% in the meridional average and up to 160% in regions covered with heavy air traffic such as Europe, the USA and the North Atlantic. This thesis investigates the quantity of long range civil subsonic aircraft NOx pollutants at cruise altitude and their subsequent implications for the upper troposphere. It discusses the concept of atmospheric NOy pollution chemistry, using computer programs developed for both total aircraft performance and 3-D chemistry transport modelling, and combinations thereof. Simulations have been conducted to predict the relationship between the NOx emissions and the environment. In addition, the thesis highlights the most important variables and derives a procedure to model the emissions from subsonic aircraft flight and to assess their impacts upon the atmosphere. Finally, some complicated problems which need further work are also mentioned.

Made available in DSpace on 2014-06-11T19:27:11Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-03-27Bitstream added on 2014-06-13T20:35:17Z : No. of bitstreams: 1 silva_rep_me_guara.pdf: 1908689 bytes, checksum: 341019e7e665818b99415ff19ade0d87 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Estudos têm sido realizados em relação à utilização de biodiesel em motores alternativos de ciclo Diesel, porém pouco material é encontrado quando se utiliza este combustível em turbinas a gás. Este trabalho analisou os parâmetros de desempenho e emissões de poluentes para várias misturas de biodiesel/querosene de aviação em um turboeixo Rover 1/S60. Os testes mostraram que não houve alterações significativas na operação do turboeixo. O estudo mostrou, também, que houve decréscimo de eficiência térmica e aumento de consumo de combustível com a utilização de misturas mais ricas em biodiesel. As emissões de poluentes também decresceram com o aumento de teor de biodiesel na mistura. / Several tests have been performed comparing diesel and several kinds of esthers (biodiesel), most in reciprocating engines but also in micro-gas-turbines. This work studies a stationary turboshaft Rover 1/S60 performance and pollution emissions in the utilization of several blends of aviation kerosene and biodiesel. The tests also show that no significative changes occurred in turboshaft operation. This study also shows an increase of fuel consumption and a decrease in thermal efficiency and a decrease of pollutant species emission as the higher biodiesel proportion at blends are used at turboshaft operation.

Resumo: Estudos têm sido realizados em relação à utilização de biodiesel em motores alternativos de ciclo Diesel, porém pouco material é encontrado quando se utiliza este combustível em turbinas a gás. Este trabalho analisou os parâmetros de desempenho e emissões de poluentes para várias misturas de biodiesel/querosene de aviação em um turboeixo Rover 1/S60. Os testes mostraram que não houve alterações significativas na operação do turboeixo. O estudo mostrou, também, que houve decréscimo de eficiência térmica e aumento de consumo de combustível com a utilização de misturas mais ricas em biodiesel. As emissões de poluentes também decresceram com o aumento de teor de biodiesel na mistura. / Abstract: Several tests have been performed comparing diesel and several kinds of esthers (biodiesel), most in reciprocating engines but also in micro-gas-turbines. This work studies a stationary turboshaft Rover 1/S60 performance and pollution emissions in the utilization of several blends of aviation kerosene and biodiesel. The tests also show that no significative changes occurred in turboshaft operation. This study also shows an increase of fuel consumption and a decrease in thermal efficiency and a decrease of pollutant species emission as the higher biodiesel proportion at blends are used at turboshaft operation. / Orientador: João Andrade de Carvalho Junior / Coorientador: Pedro Teixeira Lacava / Banca: Petronio Masanobu Tanisho / Banca: Luiz Daré Neto / Mestre