Abstract: Both 2D and 3D methods can be used for modeling a rotor system with local thermal bending， but comparisons of the two methods and their applications are still not reported. The two methods were discussed in detail based on heat transfer and rotor dynamics theories in rotor system with local thermal bending. The efficiency and accuracy of the two methods were compared through analyses of thermal field， thermal deflection and thermal bending vibration of an actual rotor system. The results show that the 2D thermal field analysis has lower accuracy but higher computational efficiency， which is suitable for concentrated heat input， while the 3D method has higher accuracy but lower computational efficiency， which is suitable for dispersed heat input.

Key words: rotor system, thermal bending, vibration, thermal field analysis, heat transfer theory, rotor dynamics