Blade Loss Studies In Low-pressure Turbines –From Blade Containment To ControlledBlade-shedding

Activities performed in the “Structural Design and Dynamic Strength” research unit of ONERA-Lille mainly aim at analysing the behaviour of aeronautical structures under dynamic transient loadings (crash, impact, explosion...). In this frame, recent studies are performed in collaboration with TURBOMECA (French turbine manufacturer) to evaluate and develop numerical methodologies for the analysis of “blade-shedding” events in low-pressure turbines. Blade-shedding is part of a safety process to preserve turbines disks from burst in the event of over-speed regime and consists in generating controlled blades ruptures in order to decrease centrifugal efforts sustained by the disks. Such a procedure however leads, on the one hand, to impacts from the released blades onto the turbine rings and containment shields and, on the other hand, to unbalance transient centrifugal efforts in the turbine, which create severe loads at the engine mounting components and bolted assemblies.