Effects of Typical Machining Errors on the Nonlinear Dynamic Characteristics of Rod-Fastened Rotor Bearing System

Liang, Yi; Liu, Heng; Wang, Nanshan

doi:10.1115/1.4034768

Cited by 7 publications

(6 citation statements)

References 12 publications

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“…Particularly, for a thin-disk, when a slant of its PAI occurs, it induces a continuously increasing rotational inertia moment of excitation with the operational speed in even a supercritical state, leading to a rapid escalation in rotor dynamic response [14,15]. This supercritical vibration has been observed in heavy gas turbine engines and aero-engines, where the slant of the turbine disk was identified as the underlying cause of elevated rotor vibration under supercritical conditions [16,17]. Therefore, it is critical to consider the effect of the slant of a thin-disk's PAI and its axial distribution on the rotor's dynamic response at high speeds.…”

Section: Introductionmentioning

confidence: 99%

Distributed Rotational Inertia Load Excitation Model and Its Impact on High-Speed Jointed Rotor Dynamic Response

Wu,

Hong,

Chen

2023

Symmetry

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Contemporary aero-engines aim for enhanced efficiency and weight reduction. They are designed to increase rotor operational speed while reducing rotor bending stiffness. This may result in bending deformation in rotor systems within the operational speed range. Such deformation can change the relative positions of rotor components, potentially causing increased mass asymmetry or unbalance. Traditional rotor dynamic models typically assume a constant rotor state. They approximate unbalance using constant mass eccentricities at certain rotor cross-sections. However, this approach has its limitations. This paper focuses on a high-speed jointed rotor system. A distributed rotational inertia load excitation model is proposed. This model explicitly considers the rotor’s variable unbalance state at different operational speeds. The study involves both simulations and experimental investigations. The results show that at high speeds, bending deformation causes the unbalance and rotational inertia load to shift from a concentrated to a distributed state. Notably, the localized rotational inertia moment from thin-disk components like turbine disks becomes significant at high speeds. This results in a rapid increase in bearing load with rotational speed. It also profoundly affects the rotor’s joints, causing interfacial slip and sudden changes in rotor vibration characteristics.

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Section: Introductionmentioning

confidence: 99%

Distributed Rotational Inertia Load Excitation Model and Its Impact on High-Speed Jointed Rotor Dynamic Response

Wu,

Hong,

Chen

2023

Symmetry

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“…Therefore, when the operational speed of a supercritical rotor is largely far away from its critical speed, the CM offset is unlikely to cause an excessive dynamic response. However, for a thin disk (i.e., disks with a ratio of polar moment of inertia I p to diameter moment of inertia I d greater than 1) with a slanted principal axis of inertia (PAI), its rotational inertia load can increase with operational speed under supercritical conditions [9,10] and cause rotor dynamic response to increase continuously, which has been found in several rotor vibration failures [11][12][13]. Therefore, considering the influence of disk slant in the dynamic response analysis of a supercritical rotor is critical.…”

Section: Introductionmentioning

confidence: 99%

Analysis of High-Speed Rotor Vibration Failure Due to Sudden Angular Deformation of Bolt Joints

Wu,

Hong,

Chen

et al. 2023

Symmetry

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As the efficiency of advanced aero engines improves, the operational speed of their rotors increases. This heightened operational speed makes the rotor dynamics highly sensitive to changes in the rotor’s mass asymmetry state, or unbalance state. During the use of a dual-spool turbofan engine, when its supercritical high-pressure rotor (HPR) exceeds a certain operational speed, the rotor’s vibration spikes and continues to increase with the operational speed until it drops sharply near the maximum operational speed. Analysis of the bolt joints in the faulty rotor reveals various phenomena such as joint interface damage, changes in bolt loosening torque distribution, and alterations in rotor initial unbalance. This paper proposes that at high operational speeds, the bolt joint of the HPR undergoes sudden angular deformation, resulting in the slanting of the principal axis of inertia of the turbine disk. This slant leads to changes in the unbalanced state of the HPR. The additional unbalance causes a sudden rotational inertia load excitation, triggering the rotor vibration failure. Subsequently, a rotor dynamic model that incorporates the angular deformation of the joints is established to simulate how this joint deformation influences the dynamic response of the rotor. The simulation results align well with the observed failure phenomenon and validate the proposed failure mechanism. Finally, troubleshooting measures are proposed and implemented in the faulty engine, effectively mitigating the vibration fault.

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“…Besides, in some cases, the machining error of rotor [ 25 – 31 ], rub-impact force and other nonlinear coupling forces [ 32 – 40 ] would also lead to bistable behaviour of rotor.…”

Section: Introductionmentioning

confidence: 99%

Study on the bistable vibration behaviour of a rod-fastened rotor-bearing system

Yang

Ren

et al. 2022

Nonlinear Dyn

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Gas turbine generator sets are widely used in IGCC system, gas-steam combine cycle, distributed energy system et al. for its advantages of low pollution, high efficiency, quick start and stop. The structure of gas turbine rotor can be divided into integral rotor and rod-fastened rotor. Experimental study shows that the vibration signal, especially the displacement signal, of the rod-fastened rotor will increase/decrease greatly in a small interval of rotating speed. The reason for this phenomenon is the unique structure of the rod-fastened rotor, namely the interfaces between discs. In this paper, based on the Lagrange equation, the equation of motion of a rod-fastened rotor-bearing system considering the damping of the contact interface is established. The bistable behaviour and hysteretic cycle, also called the jumping phenomenon in engineering, are revealed. In addition, a test bench of the rod-fastened rotor-bearing system is built. The bistable behaviour and hysteretic cycle are experimentally proven, and the effect of the eccentric distance of the rotor on the bistable behaviour is experimentally explored.

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Effects of Typical Machining Errors on the Nonlinear Dynamic Characteristics of Rod-Fastened Rotor Bearing System

Cited by 7 publications

References 12 publications

Distributed Rotational Inertia Load Excitation Model and Its Impact on High-Speed Jointed Rotor Dynamic Response

Distributed Rotational Inertia Load Excitation Model and Its Impact on High-Speed Jointed Rotor Dynamic Response

Analysis of High-Speed Rotor Vibration Failure Due to Sudden Angular Deformation of Bolt Joints

Study on the bistable vibration behaviour of a rod-fastened rotor-bearing system

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