Modeling of Casing Containment in an Overspeeding Turbine Stage

This paper is on the structural characterization of a turbine casing in terms of blade containment. Gas turbines experience unintentional blade loss events in service for various reasons such as fatigue and the engines are certified on the basis that these events do not cause hazardous outcomes. In certain conditions, such as permanent loss of load after a shaft or transmission failure, the turbine stage(s) may accelerate to excessively high speeds creating the possibility of disk burst. An ls-dyna explicit finite element model of a bullet to plate experiment has been prepared with flat nose projectiles. Following the method verification, the procedure was applied for a turbine stage with a single layer and a multilayer casing to assess the performance of those in a blade-off at overspeed conditions when turbine experiences permanent loss of load. The intention with the multilayer casing is to allow penetration within the first layer to dissipate the energy of the fragments and to contain them within the second layer.