Noise Reduction of Aero-Engines Using Innovative Stators With Leading Edge Features

This work is dedicated to the aeroacoustic characterization of low-noise outlet guide vanes with leading edge features, designed for the reduction of UHBR turbofan noise in the framework of European Project Cleansky 2 H2020 INNOSTAT. Two innovative low-noise OGV concepts with leading edge serrations and slits were designed, fabricated, and tested on the ECL5 -CATANA fan stage, which is used as reference for the aeroacoustic performance of a realistic turbofan test-case. Detailed aerodynamic and acoustic measurements were performed for different operating conditions of the fan stage. The instrumentation includes rakes, a far-field microphone array, and flush-mounted microphones to analyze the modal content of the fan-OGV noise. Both low-noise OGV concepts show promising results from an aeroacoustic perspective. Broadband noise can be reduced up to 4 dB for the slitted OGV and up to 6 dB for the serrated OGV in upstream direction. Downstream of the fan-OGV stage, the in-duct modal decomposition shows a broadband noise reduction of approximately 8 dB for the high-order modes, which leads to a reduction in the acoustic power of 5 to 10 dB for both concepts over a large portion of the frequency range. Additionally, a significant attenuation of the blade passing frequency harmonics can be observed in the upstream and downstream directions (up to 13 dB for the slitted OGV). These findings suggest that innovative leading edge features on the OGVs can be useful to reduce broadband and tonal interaction noise in modern aero-engines.