Thermocyclic fatigue and destruction of high pressure turbine blades in their critical sections

Abstract

In the article the critical sections and points at the leading edges of the airfoils of high-pressure turbines were reasonably defined for experimental studies of thermocyclic durability. Experimental studies of thermocyclic durability were performed for the samples of heatproof alloys for the cyclic change parameters in extreme temperatures and thermomechanical stresses that exert at the starting and running down of aircraft gas turbine engines and ground gas turbine power plants. The influence of protective coatings on thermocyclic durability of alloys and parts is mentioned in the article. The article describes the methods of determination the thermal stress in the blades. It is emphasized that extreme thermal stresses of compression in the edges of nozzle vanes and stretch on the pressure side of the airfoil occur on the operating mode "starting", and the cracks are revealed mainly on the mode "shutdown". In the intermediate stages of the flight cycle the do not exceed of the yield strength of the blade material and do not significantly affect there lative thermocycle durability of heatproof alloys. The destruction of the blades of high-pressure turbines in their cross sections along the airfoil shroud platform, in the zone of maximum temperature sand in the root sections explained from the position of the three– and multi component approach.