INFLUENCE OF TEST CONDITIONS ON THE AERODYNAMIC AND AEROELASTIC BEHAVIOR OF THE ECL5/CATANA FAN

Abstract To improve the understanding and enhance the predictibility of Non-Synchronous Vibration (NSV) and rotating stall an extensive experimental campaign was conducted with the open-test-case ECL5, which is representative of modern Ultra-High-Bypass-Ratio (UHBR) fan architectures. These experiments indicate an influence of test conditions (absence of Turbulence Control Screen (TCS), shortened intake configuration, mechanical rotation speed) on the measured aerodynamic and aeroelastic behavior of the fan stage. This influence occurs superimposed to the actual parameter under investigation (for example structural mistuning) and must be clearly characterized to avoid misleading data interpretation. Based on a detailed investigation of several test conditions, the paper provides a characterization of different influential parameters. One main outcome is the impact of mechanical rotation speed on NSV amplitudes at subsonic operating conditions. This influence challenges the comparability of different rotor and facility configurations since experiments are usually conducted at corrected mechanical speed (to account for changing atmospheric conditions) to achieve Mach similarity. The findings of the study clearly emphasize, that standard experimental procedures have to be adapted to account for identified effects.