Theoretical and experimental study on dynamics of a statically indeterminate rotor system with misalignment

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Journal of Vibration and Shock ›› 2021, Vol. 40 ›› Issue (16) : 159-165.

ZHAO Guang1,WANG Tingyue1,LI Shengxiang2,LI Fangzhong3,MA Wensheng3

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Abstract

Misalignment of a multi-support rotor system is one of the most common fault conditions.A low-pressure rotor system of aero-engine uses spline joint for connecting, which constitutes statically an indeterminate rotor system (SIRS) with three elastic supports.The inherent defect of SIRS is extremely sensitive to misalignment.In this paper, an analytical dynamic model of SIRS was derived using a combination of the force method and the virtual work principle about the D’Alembert principle under alignment and misalignment of turbine back support conditions, and misalignment dynamic loads were detailed derived to determine the natural frequency and vibration responses.In this paper, the aeroengine hyperstatic rotor system was taken as the research object, and the analytical model derivation and experimental verification were carried out for its complete alignment and tail fulcrum misalignment and both theoretical and experimental results agree well.As a result, with the increase of misalignment, frequency multiplication components occur, 2X component and increase linearly, the orbits change from ellipse to inside “8” shape.Due to the structural particularity of SIRS, the appearance of TBS misalignment which generates the dynamic external excitations，makes the response of low-pressure turbine more severely.

Key words

statically indeterminate rotor system(SIRS) / misalignment / analytical model / dynamics

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ZHAO Guang,WANG Tingyue,LI Shengxiang,LI Fangzhong,MA Wensheng3. Theoretical and experimental study on dynamics of a statically indeterminate rotor system with misalignment[J]. Journal of Vibration and Shock, 2021, 40(16): 159-165

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