A review on modelling and dynamic analysis of viscoelastic rotor systems

Purpose The purpose of this study is to bring down collective information about various issues encountered in modelling of rotor systems. Design/methodology/approach The most important and basic part of “rotor dynamics” is the study related to its different modelling techniques which further involves the analysis of shaft for understanding the system potential, competence and reliability. The issues addressed in this study are classified mainly into two parts: the initial part gives out a vast overview of significant problems as well as different techniques applied to encounter modelling of rotor systems, while the latter part of the study describes the post-processing problem that occurs while performing the dynamic analysis. Findings The review incorporates the most important research works that have already placed a benchmark right from the beginning as well as the recent works that are still being carried out to further produce better outcomes. The review concludes with the modal analysis of rotor shaft to show the importance of mathematical model through its dynamic behaviour. Originality/value A critical literature review on the modelling techniques of rotor shaft systems is provided from earliest to latest along with its real-time application in different research and industrial fields.

Analysis on Influences of Squeeze Film Damper on Vibrations of Rotor System in Aeroengine

Squeeze film damper (SFD) is widely used in the vibration suppression of aeroengine rotor systems, but will cause complex motions of the rotor system under specific operating conditions. In this paper, a lumped-mass dynamic model of the high-pressure rotor system in an aeroengine is established, and the nonlinear stiffness and damping formula of SFD are introduced into the above model. The vibration responses of the rotor system under different rotating speeds and with different unbalances are investigated numerically, and the influence of SFD on the rotor system vibration and the change of suppression ability are compared and analyzed. The results show that in the case of high speed, together with a small unbalance, the rotor system will perform a complex vibration or a bistable vibration due to SFD. If the unbalance is properly increased under the same case of high speed, the vibration of the rotor becomes single-harmonic and the bistable vibration disappears. The research results can provide a helpful reference for analyzing complex vibration mechanisms of the rotor system with SFD and achieving an effective vibration suppression through unbalance regulation.

A Method for Predicting the Influences of Bearing Support Stiffness and Position on the Vibrations of a Flexible Rotor System

The bearing support stiffness and position can greatly affect the vibrations of flexible rotor systems (FRSs). However, most previous works only focused on the effect of the bearing support stiffness on the critical speeds or modal characteristics including the natural frequencies and mode shapes of rigid rotor systems (RRSs). The previous studies missed the combined effects of the bearing support stiffness and position. To overcome this issue, an analytical method of a FRS based on the finite element (FE) method is proposed. Our model considers the bearing support stiffness and rotational inertia of FRS. The frequency equation of FRS is established for solving the critical speeds. The critical speeds and modal deformations of FRS from our model and the numerical model based on a commercial software are compared to verify the effectiveness of the presented method. The effects of the bearing support stiffness and position on the critical speeds of FRS are analyzed. The results show that the critical speeds are positively correlated with the bearing support stiffness. The critical speeds of FRS are also greatly affected by the bearing position. This study can provide some guidance for the optimization design method of bearing support stiffness and position in FRSs.

Recent advances in reliability analysis of aeroengine rotor system: a review

PurposeTo provide valuable information for scholars to grasp the current situations, hotspots and future development trends of reliability analysis area.Design/methodology/approachIn this paper, recent researches on efficient reliability analysis and applications in complex engineering structures like aeroengine rotor systems are reviewd.FindingsThe recent reliability analysis advances of engineering application in aeroengine rotor system are highlighted, it is worth pointing out that the surrogate model methods hold great efficiency and accuracy advantages in the complex reliability analysis of aeroengine rotor system, since its strong computing power can effectively reduce the analysis time consumption and accelerate the development procedures of aeroengine. Moreover, considering the multi-objective, multi-disciplinary, high-dimensionality and time-varying problems are the common problems in various complex engineering fields, the surrogate model methods and its developed methods also have broad application prospects in the future.Originality/valueFor the strong demand for efficient reliability design technique, this review paper may help to highlights the benefits of reliability analysis methods not only in academia but also in practical engineering application like aeroengine rotor system.

An analysis method for the performance of compliant cylindrical intershaft gas film seal considering centrifugal expansion effect

A compliant cylindrical gas film seal has the potential to adapt to the complex operating conditions of a dual-rotor aeroengine, with radial runout and eccentricity, due to its special structural characteristics. To accurately investigate the seal performance of a compliant cylindrical gas film seal on dual-rotor shafts, an aeroelastic coupling method is proposed. This method analyzes the performance of a compliant cylindrical intershaft gas film seal by taking the centrifugal expansion effect into consideration. The seal performance under homodromy and counter-rotating conditions, with and without the centrifugal expansion effect, is calculated, and various performance parameters are compared and analyzed. Furthermore, the influence mechanism of the direction of rotation of the two rotors on seal performance is revealed. The results show that seal performance under homodromy condition is greater than under counter-rotating condition, and for an aeroengine under homodromy condition, it is advantageous to apply the compliant cylindrical intershaft gas film seal. The effect of centrifugal expansion (in large-diameter and high-speed rotors) and rotor eccentricity on the performance of a compliant cylindrical intershaft gas film seal, as well as the impact of inner and outer rotor speed on leakage rate, are analyzed and presented in this study. The proposed aeroelastic coupling method provides a promising guidance for the performance analysis of the compliant cylindrical gas film seal in single and dual- rotor systems.