14th European Conference on Turbomachinery Fluid dynamics & Thermodynamics
Authors
Abstract
Ultra High Bypass Ratio (UHBR) fan is a promising solution for the next decades to improve the turbofans efficiency and to reduce the environmental impact of the aeronautical propulsion. The high aspect ratio and the use of composite material for these fan blade induce new coupling problematics between aerodynamic, aeroelastic and aeroacoustic phenomena. In this context, a new open-test-case fan stage ECL5 is provided to the turbomachinery community within the European CleanSky-2 project CATANA. In Part-1 of this publication, the test case is introduced with details on geometry, methodology and aerodynamic design of the whole stage, whereas Part-2 focuses on structure dynamics and aeromechanical stability. This paper aims to provide the mechanical and aeroelastic stability characteristics of the fan stage obtained with a state-of-art industrial design process. These analyses enable to ensure the integrity for the anticipated experimental campaigns. The fan blades are fabricated of unidirectional carbon fibres and epoxy composite layers. Fibre orientations of each layer are parameters which enable to modify the mechanical behaviour with minimal impact on the aerodynamic performance. Details on the structural properties, the manufacturing process and the layer orientations will be presented. Mechanical analysis of the fan, determined by finite element method, is provided. The specific methodology to account for the anisotropy of the blade composite structure is introduced. The static deformation along the working line and first mechanical modes of the fan are described and discussed in the context of aeroelastic interactions. To be representative of industrial configurations and to enable complete experimental campaigns, it is necessary that the fan presents stable operating conditions at every planned experimental rotation speed. Its aeroelastic stability is investigated on the 3D isolated blade with time-linearized method. This method provides similar results to unsteady simulations but with lower computational cost in the absence of circumferentially convected aerodynamic disturbances occurring near stall. Thus, the aeroelastic stability is characterised across the complete operating range for the first three blade eigenmodes.
ETC2021-625
Paper is available for download