In gas turbine power plants, a fan is used as a cooling system to dissipate generated heat in coils (copper conductors) and generator electric circuits at the end sides of its rotor. In some cases, fracture of blades causes a short circuit between rotor and stator and consequently generator explosion and financial problems. The fracture of cooling fan blades has occurred five times at the turbine side of the generator in our case of study, just 100hr after resuming operations after an overhaul. Using numerical analysis as well as laboratory investigation – including visual inspections, metallography and SEM – can help better find failure problems that cause blade failures. A series of numerical analysis was performed to diagnose the possible cause of failure. CFD analysis is used to study the airflow distribution in order to observe probable separation phenomenon and pressure forces as they are imposed on fan blades due to operation. A finite element method was utilized to determine the stresses and dynamic characteristics of the fan blade (natural frequencies, stresses and vibrations).
Analizowano zużycie erozyjne łopatki wirnika wentylatora. Obliczone wartości naprężeń kontaktowych wskazują na możliwość istnienia dwóch mechanizmów zniszczenia podczas: 1 - prostopadłego uderzenia, 2 - poślizgu z udziałem sił tarcia. Materiał do pracy w warunkach erozji strumieniowo-ściernej powinien posiadać możliwie wysoką granicę plastyczności i mały moduł Younga.
EN
Erosion wear of a fan rotor blade is analysed in the paper. The calculated values of contact stresses show that mechanisms of destruction may exist during: 1) perpendicular impact, 2) slip with participation of friction forces. Materials used in the paper in conditions of stream-abrasive erosion should have potentially high yield field and low Young's modulus.
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