Multidisciplinary Assessment of Foreign Object Damage (FOD) Sensitive Regions on a Compressor Rotor Blade

Abstract During takeoff and landing, aero engines often ingest foreign objects which can damage the airfoils. These events can have a significant impact on the safety of the engine, particularly due to the operating load condition of gas turbines throughout their service life. In addition, the appearance of dents or cracks along the blade leads to surface damage, which in turn affects the structural mechanics integrity and the overall aerodynamic performance. In order to prevent safety concerns and high maintenance costs, blades with improved FOD robustness are being sought. In this prospect, the prediction of airfoil regions with high sensitivity to FOD plays a crucial role for later optimization. The aim of this work is to identify these areas, focusing on two aspects: the detection of airfoil regions with the highest probability of foreign object impact, and the evaluation of FOD critical areas through structural mechanics and aerodynamics evaluation. The first objective was achieved with the creation of a surface defect map obtained using a white light scanning technique. The structural mechanical investigation involved the numerical calculation of the stress concentration factor, which predicts the allowable stress increase caused by a local damage. From the aerodynamic perspective, the same assessment was carried out by placing a sample FOD at six positions along the airfoil edge. By comparing the compressor performance for the same damage at different heights, the most sensitive region was identified. Finally, the achieved multidisciplinary overview highlights potential regions to be optimized in future airfoil design in order to increase the overall robustness against FOD.