Principles of Thermodynamic Preliminary Design of Civil Turbofan Engines

The design process of a civil turbofan engine is a continuous iteration among a variety of disciplines. From the performance point of view, its main target is the accomplishment of a specified thermodynamic cycle, which is optimised in terms of block fuel for a specified airframe and typical mission, while meeting a variety of multidisciplinary restrictions. Engine performance and component areas are engaged in an interactive collaboration. Performance provides component designers with precious information regarding component operating points and boundary conditions at critical flight conditions and power levels. In the opposite direction, component design is revised to provide performance with the most up-to-date overall component behaviour. Such an iterative process is initiated based on fundamental assumptions regarding the engine architecture, the available proven technology and the customer demands. Scope of the current work is to investigate the effect of engine architecture, component related restrictions and aircraft requirements on engine performance during the preliminary design phase. Given the multi-disciplinary nature of engine design, the conflicting interaction of various design parameters is discussed considering aerodynamic, mechanical and lifing issues. The parameters selected to form the mathematical problem all reflect a level of compromise among the various disciplines. The study aims at justifying the result of an optimal solution, which satisfies the requirements and restrictions set.Copyright © 2009 by Rolls-Royce plc