Evaluation of the Energy Dissipated as Friction/Heat Between Turbines Following Shaft Failure

Abstract

The prevention of primary failure that may lead to a potentially hazardous event has always been a predominant aim in engine design and development. In the event of a shaft failure event, the turbine operates under high power conditions which may lead to blade release or disc burst. A potential mechanism to eliminate quickly the power of the free running turbine involves the dissipation of the kinetic energy as friction/heat due to structural interaction between turbines. In the scope of this paper, a finite element model is developed to study the energy dissipated due to structural interaction. A coupled thermo-mechanical analysis is carried out taking into account the temperature increase in the turbines’ structure following the severe impact. The coupled thermo-mechanical analysis addresses the effects of temperature rise and material softening on the evolution of the shaft failure event. The part of the kinetic energy converted into thermal and the wear rate of the seal segment structure are investigated in order to assess the potential of the contact mechanisms to act towards reducing the power of the free running turbine as quickly as possible due to blade tangling. Finally, the dependency of frictional energy and wear rate on the structural damping and the definition of the thermal material model have been studied highlighting their importance in the impact simulations.