Some challenges in turbomachinery for propulsion

Authors

Hans Mårtensson - GKN Aerospace Engines Systems

Abstract

Challenges facing manufacturers in the turbomachinery propulsion industry are many and evolve over time. Performance improvements are introduced with every new generation giving machines with lower environmental impact and fuel cost. In propulsion applications safety, weight and packaging are particularly important to the design. Beginning with aircraft engines a brief description is given of some of what designers need to relate to. For space propulsion a background is given to some of the issues that govern the design of the turbomachines. From a manufacturer’s perspective, university research is important for the development of both skilled co-workers and for creating knowledge that can be used in future designs. Here the openness of academic research needs to meet with the needs of industrial secrecy. A context for this is described where the open research can work within a notional design, a virtual product design where relevant data can be shared more openly. Integration of components in the engine is a complex task with interfaces to the surrounding components, in particular regarding the engine structures. An example of how this is the inter compressor structure. This component needs to accommodate critical structural loads, while accommodating system services and satisfying aerodynamic requirements. In industry, CFD has become a standard tool in design of turbomachinery allowing advanced 3D aerodynamic shapes. There still remains areas where regular CFD methods should be improved in order to be used with optimization methods, as for instance for the stalling behavior of compressors. While CFD based computational aeroacoustics has emerged as a powerful tool, research is still needed in several computational areas, as well as to allow effective integration of liners to reduce noise from the engine. Blade vibration is addressed in design, but may also be encountered in service. Here both design methods to improve margins and analysis methods that allow the analysis of aeromechanic vibrations are desirable. An important aspect of any design is that it should be insensitive to variation to some extent. Finding ways to support this with modern design methods is a way to obtain better designs, and more quickly find the effects of manufacturing methods. This will be an important part of Industry 4.0 thinking that will transform industrial methods. New materials and industrial technologies are emerging that in part change what we can hope to achieve in the future, in terms of performance but manufacturing and cost. Research is also needed to address a wide spectrum of issues that ranges from traditional mechanical engineering analyses and validation to multidisciplinary optimization (MDO) of systems. MDO can in the example shown, be viewed as a way of rapidly working with balancing of requirements to support the integration of new technologies. The use of more computer power in all stages of design, production and use will mean new opportunities for improvement to propulsion.