Decreasing pollutants from aircraft emissions
Flying at high altitudes, airplanes and helicopters emit various harmful substances, such as NOx that are considered responsible for major environmental problems. Not only do they affect the air quality of the region, but they may also have significant impact on the global climate. The ever-increasing accumulation of these oxides, among others, on the upper atmosphere has been proven responsible for environmentally unfriendly phenomena, such as the greenhouse effect. In response, this project focused on exploring the capabilities of low NOx emission technologies in several combustors used in aircraft engines. Complying with regulations from the International Civil Aviation Organisation, the objective was to achieve a reduction target of 60%. The combustors under study were either modular or full-scale and covered the various sizes and the different operating conditions of small, medium and large engines. The results showed that for small engines a 50% reduction was possible, while for medium engines a 60% reduction could be accomplished. As far as large engines were concerned, the study had to resolve unexpected problems. Nevertheless the derived results were satisfactory for modules using the Lean Premixed Prevaporised (LPP) concept for injection systems. Additionally, the potentialities of the Rich Quenched Lean (RQL) combustion concept and cooling topics were also investigated. Furthermore, a focused generics activity facilitated the development and evaluation of new analytical tools, technology and advanced design concepts for optimisation of LPP and combustors. Computational Fluid Dynamics (CFD) codes were developed that may provide increased accuracy and reliability when evaluating different combustor technologies. Involving six aero-engine manufacturers and sixteen research organisations, this project may contribute significantly to the future growth of air transport without environmentally adverse effects.
