Browsing by Author "Noppel, F. G."
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Item Open Access Comparison of unconventional aero engine architectures(Cranfield University, 2011-04-30) Noppel, F. G.; Singh, R.In the light of global warming, the associated socio economical consequences, and the projected shortage of natural energy resources and ever rising oil prices, this thesis examines the potential for unconventional aero engine architectures to reduce fuel consumption of passenger aircraft. Current aircraft engines are based on the Brayton cycle, where the working fluid successively experiences isentropic compression, isobaric combustion, and isentropic expansion. Deviations from the ideal cycle in real engines occur through component inefficiencies. The maximum achievable thermodynamic efficiency of the Brayton cycle increases hand in hand with its peak cycle temperature. Since the peak cycle temperature is limited by material properties of the turbine, the maximum cycle efficiency of current jet engines is limited by the laws of thermodynamics. Hence, efficiency improvements of jet engines beyond what is possible with conventional turbofan designs are only feasible through unconventional engine architecture. Several technologies enabling unconventional engine architectures for aircraft propulsion have been identified. They include wave rotor, pulse detonation and internal combustion. These technologies are merged with conventional jet engine technology to form hybrid designs. A one dimensional engine performance model was developed to calculate the performance and allow a comparison of the hybrid cycles with a conventional turbofan cycle. Gradient optimisation techniques were applied to the allow comparison of the best possible designs. Results suggest that of the examined cycles, the hybrid internal combustion cycle has the best potential for fuel savings compared to conventional turbofan cycles.Item Open Access Contrail and cirrus cloud avoidance technology(Cranfield University, 2007-10) Noppel, F. G.; Singh, R.Civil aviation, providing transport to connect people, cultures and economies, is situated at the heart of globalisation. Since its earliest days, it has grown along with every other part of the industrialised society and experienced growth rates exceeding that of global GDP. Projections suggest that future air traffic emissions will play an increasingly important role in the contribution to global warming, which is regarded to be a serious threat to earth’s socio-ecological systems. Air traffic contributes to the overall anthropogenic radiative forcing, a metric denoting perturbations in the earth’s radiation budget, by the emission of greenhouse gases and aerosols, and also by the generation of high ice clouds, commonly known as contrails. Recent studies suggest that the radiative forcing resulting from contrails is potentially higher than that of all other air-traffic pollutants combined. In light of this, contrail avoidance is attracting increasing interest from the aeronautical community. An important contribution to the understanding of the problem in a wider context is made in this thesis, alongside proposals for short, mid and long term strategies for contrail avoidance. These are in particular the optimisation of the aircraft for contrail avoidance, the application of remotely induced heat to suppress contrail formation, and a novel engine concept that exhibits the potential for a reduction of all emissions simultaneously. Aircraft optimisation deals with the adaptation of existing technology for more environmentally compatible air transport, whereas the latter two approaches are breakthrough technologies of a more disruptive character covered by several patents resulting from this research. Short and mid term strategies are accompanied by an increase in carbon dioxide emissions. A study examining the long-term impact of aviation carbon dioxide emissions relative to that of contrails suggests that in order to achieve more sustainable air transport, the avoidance of contrails is inevitable. However, as the short-term impact of contrails is less severe, postponing contrail avoidance until the associated increase in carbon dioxide emissions is less significant could be a better way to deal with the problem.