A tool based on a Techno-economic and Environmental Risk Assessment (TERA)framework is useful at the preliminary stage of an aero engine design process, toconceive and assess engines with minimum environmental impact and lowest cost ofownership, in a variety of emission legislation and taxation policy scenarios.This research was performed as part of the EU FP6 New Aero engine Core concepts(NEWAC) programme which was established to assess the potential of innovative gasturbine core technologies to enhance thermal efficiency thereby reducing CO2emissions and fuel consumption. A representative prediction of engine life and missionfuel burn at the earliest possible design stage is a crucial task that can provide anindication of the approximate overall engine direct operating costs. Two aero engines,a conventional turbofan and a conceptual intercooled turbofan, were assessed andoptimised using the TERA approach to identify the designs that provided the maximumtime between overhaul (and therefore the minimum maintenance costs). In order toperform these assessments (which included sensitivity and parametric analyses, andoptimisation studies) several models were developed and integrated in an optimisationframework. A substantial effort was devoted to the development of a detailed lifingmodel that calculates the engine life with a reasonable level of accuracy by integratingphysics based oxidation, creep and fatigue models.The results obtained from the study demonstrate that an engine optimised formaximum time between overhaul requires a lower overall pressure ratio and specificthrust but this comes at the cost of lower thermal efficiency and therefore highermission fuel burn.The main contribution to knowledge of this work is a multidisciplinary TERAassessment of a novel intercooled conceptual aero engine. Particular emphasis isplaced on the design space exploration and optimisation studies to identify the designsthat may offer the largest time between overhaul. The consequent implicationstherefore this may have on mission fuel burn and direct operating costs.In addition to refining the various TERA models, one of the main recommendations forfurther work is to optimise the engines for minimum direct operating cost to identify thebest economic compromise between engine life and mission fuel burn. This can bedone by considering different fuel prices and under a variety of hypothetical emissiontaxation scenarios, to identify the circumstances in which intercooled enginetechnology may become economically viable.
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