Propulsion Installation Modelling for geared Ultra-high bypass ratio engine cycle design

Other conference contribution, 2020

About 3% of the greenhouse gas emissions in the EU are derived from aviation. By 2020, the global international aviation emissions are assumed to be approximately 70% higher than those in 2005 and a strong continued growth in travel demand is expected at least up until 2035. A radical reduction of emissions have to occur on multiple fronts ranging from incremental improvements of advanced propulsion systems to new fuels and electrification. The desire to get higher efficiencies has contributed to the movement from turbojet engines to today's high bypass ratio turbofan engines. The fuel consumption and propulsive efficiency of turbofan engines are highly dependent on the fan pressure ratio (FPR). Decreasing FPR gives an improved fuel and propulsive efficiency as long as installation losses do not exceed potential benefits. As part of the Clean Sky project IVANHOE, new types of nacelles will be developed to enable installation of propulsion systems with radically increased bypass ratio and reduced FPR. In this work the process of describing and selecting a suitable propulsion system is described. The cycle is defined by a multidisciplinary analysis considering nacelle drag, propulsion system weight and engine performance. Effects of variation in turbine cooling with cycle change and small size turbomachinery efficiency is considered defining the core size and pressure ratio. Variations in installed SFC with fan diameter choice is quantified along a suboptimal line of fan pressure ratio and bypass ratio for a specific optimal overall pressure ratio. The final cycle choice is presented.