AN INVESTIGATION ON THE CAUSES OF A ROTOR BENDING A.ND ITS THERMAL STRAIGHTENING

Distortion or bend in a turbine rotor (especially hip rotors) may be caused by a numberof factors, either singularl) or in combination. in general. the causes of rotor bend can be classifiedinvartably in two categories: rapidly forming permanent rotur bends and/or slower forming rotorbends. which could trip the turbines' emergency stop. one of the major modi fy ing solutions for rapidrepairing or bent rotors is hot spotting. for this purpose. after the initial tests (visual inspection.chemical analysis, nondcstr ict ive hardness). the hot spotting was performed seven consecutive times.the results of experimental investigations and experiences with different temperatures and timesshowed that, the 690 ± 2uc and 210 s. nrc as an optimum t mperaturc and time respectively. i' i' hotspotting which c: n provide. a noticeable srraightening in bent areas, in addition to having no affects onmechanica l properties. also. this results were simulated by f.e,m in view or heat distribution indifferent temperatures in three states (without insulation. with moisture and dry insulation). in order infind out the optimum restra ii t effects around hot spot area.