14th European Conference on Turbomachinery Fluid dynamics & Thermodynamics
Consequent application of composite rotors enables disruptive design possibilities but demands for a fundamental understanding of the dynamic behaviour to ensure robust design and safe operation. The sensitivity to multi-physical resonance between aerodynamic, structure-dynamic and acoustic phenomena is amplified in modern low speed fan designs for UHBR application. Very thin blades, which are required to maintain high efficiency at transonic flow conditions, are flexible and prone to vibrations. As a result, aeroelastic and aeroacoustic problems increasingly set the stability limit.Test cases of representative geometries without industrial restrictions are a key element of an open scientific culture but currently non-existent in the turbomachinery community. The most commonly used test cases in computational fluid dynamics (e.g. NASA Rotor37/67; TUD Rotor 1 etc.) were designed over two decades ago, and their aeroelastic characteristics are not representative of modern turbomachinery. Also, available experiments have not been conducted with a focus on coupling-phenomena and hence did not comprise multi-physical instrumentation. In order to provide a multi-physical validation benchmark representative of near-future UHBR fan concepts, the open-test-case fan stage ECL5 has been developed at Ecole Centrale de Lyon. Design intention was to develop a geometry with high efficiency and a wide stability range that can be realized using layered carbon fibre composites. The final design iteration of the fan stage is currently fabricated and will be experimentally tested within the European CleanSky-2 project CATANA (Composite Aeroelastics and Aeroacoustics). 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. An analysis of the calculated aerodynamic performance with a focus on critical flow structures like tip-leakage flow, radial flow migration and flow separations is presented. Furthermore, details on the experimental campaign comprising multi-physical instrumentation anticipated for 2021 are given to highlight the research focus. Finally, the structure of the opening and dissemination of the test case are laid out with the goal to encourage researchers to conduct simulations on the geometry that may be used to align detailed measurements which are anticipated for 2022.