Emissions modelling for engine cycle and aircraft trajectory optimisation

The aviation industry is currently experiencing a growth rate of about 4% per annum and this trend is expected to continue into the future. One concern about this growth rate is the impact it will have on the environment particularly in terms of emissions of CO2, NOx and relatively recently also cirrus clouds induced by contrails. The ACARE has set emissions reduction targets of 50% reduction of CO2 and noise and 80% reduction of NOx by 2020 relative to Y2000 technology. Clean Sky and other large EU collaborative projects have been launched in an effort to identify new, more efficient, aircraft and engine technologies, greener operational and asset management practices and lower life cycle emissions. This PhD research was funded by and contributed to the Systems for Green Operations Integrated Technology Demonstrator (SGO-ITD) of the Clean Sky project. The key contribution to knowledge of this research is the development and application of a methodology for simultaneous optimisation of aircraft trajectories and engine cycles. Previous studies on aircraft trajectory optimisation studies, published in the public domain, are based on relatively low fidelity models. The case studies presented in this thesis are multi-objective and based on higher fidelity, verified aircraft, engine and emissions models and also include assessments of conceptual engines with conceptual LPP combustors. The first task involved the development of reactor based NOx emission prediction models for a conventional aero gas turbine combustor and a novel conceptual lean pre-mixed pre-vaporised combustor. A persistent contrails prediction model was also developed. A multi-disciplinary framework comprising a genetic algorithm based optimiser integrated with an engine performance, an aircraft performance and an emission prediction model was then developed. The framework was initially used to perform multi-disciplinary aircraft trajectory optimisation studies and subsequently both aircraft trajectory and engine cycle optimisation studies simultaneously to assess trade-offs between mission fuel burn, flight time, NOx production and persistent contrails formation ... [cont.].