Thermal failure of a second rotor stage in heavy duty gas turbine. (September 2020) - Sławiński, Daniel
Highlights: There was a thermal failure of the blade system in the gas turbine. The crack origins were not covered by corrosion products and material defects. Maximum stress zones overlap the crack origins. The main cause of the failure was the thermal elongation of the blade system. Crack initiation was accelerated by abrasion the labyrinth seal about the corps. Abstract: The impulse mode of operation and the supply of various types of fuels causes frequent failures even in the heavy duty gas turbines. The paper presents the ravages of second rotor stage failure in a gas turbine. The excessive thermal elongation rise caused by fuel change was indicated as the main cause. We applied nonlinear numerical analysis, preceded by thermodynamic calculations of the turbine and visual inspection of the effects of failure. Simulations were performed on undamaged blade geometry under load resulting from combustion: nominal fuel and the changed fuel. Thermodynamic calculations demonstrated a 70 °C increase in temperature using the changed fuel. The blade tip displacements demonstrated the possibility of abrasion. The amount of displacement of the tip of the turbine blade with increasing pressure or increasing rotational speed do not pose as great a threat, as does the increase in the temperature. To maintain long-term and safe operation of a gas turbine, it is necessary to strictly observe the manufacturer's guidelines regarding fuel composition. If during the operation of a gas turbine it is likely that it can be powered by various types of fuels, then the structure should have adequate effort reserves and working tolerances.