scholarly journals Modeling Cantilever Branch Structure of Aero-Engine Power Turbine and Analyzing Its Influence

2018 ◽  
Vol 36 (4) ◽  
pp. 728-734 ◽  
Author(s):  
Yebao Xia ◽  
Xingmin Ren ◽  
Yongfeng Yang
Keyword(s):  
Critical Speed ◽  
Vibration Mode ◽  
Structural Parameters ◽  
Rotor System ◽  
Unbalance Response ◽  
Power Turbine ◽  
Aero Engine ◽  
Turbine Component ◽  
Calculation Results ◽  
Turbine Disks

In the power turbine component of an aero-engine, there exists a unique cantilever branch structure, on which turbine disks are mounted. Due to the cantilever's characteristics, this structure exhibits a vibration of large amplitude; thus its characteristics need to be studied in detail.In this paper, the motion equations combining the structure and the shaft were deduced; then its vibration mode was given, and the criticl speed was computed; finally the unbalance response of an integrated rotor system was simulated.The calculation results are compared with the simulation results without considering the branch structure.Some key parameters' influences are studied thoroughly, e.g., the branch shaft's length, the flange's offset and the installation orientation. As the results show, the branch structure has a large influence on the vibration mode and critical speed of the rotor system, thus it should not be simplified and ignored in modelling; After adjusting the branch structure's parameters, the characteristics of a vibration mode do not change, and the effects of branch structural parameters on critical speed are closely related to the corresponding vibration mode; the bending stiffness and the critical speed of the rotor system both decreased with increasing branch shaft's length; if reducing the flange's offset and fabricating the branch structure reversely, a sharp increase in the unbalance response of the turbine disc will occur. In conclusion, the dynamical characteristics of the integrated rotor system can be optimized through reasonably designing the branch structure.

Multi Objective Optimisation of an Aero Engine Rotor System Using Nondominated Sorting Genetic Algorithm (NSGA)

2017 ◽  
Author(s):  
Joseph Shibu Kalloor ◽  
Ch. Kanna Babu ◽  
Girish K. Degaonkar ◽  
K. Shankar
Keyword(s):  
Genetic Algorithm ◽  
Critical Speed ◽  
Rotor System ◽  
Pareto Optimal ◽  
Multi Objective ◽  
Rayleigh Beam ◽  
Unbalance Response ◽  
Aero Engine ◽  
Nondominated Sorting ◽  
Engine Rotor

A comprehensive multi-objective optimisation methodology is presented and applied to a practical aero engine rotor system. A variant of Nondominated Sorting Genetic Algorithm (NSGA) is employed to simultaneously minimise the weight and unbalance response of the rotor system with restriction imposed on critical speed. Rayleigh beam is used in Finite Element Method (FEM) implemented in-house developed MATLAB code for analysis. The results of practical interest are achieved through bearing-pedestal model and eigenvalue based Rayleigh damping model. Pareto optimal solutions generated and best solution selected with the help of response surface approximation of the Pareto optimal front. The outcome of the paper is a minimum weight and minimum unbalance response rotor system which satisfied the critical speed constraints.

Electro-Rheological Multi-layer Squeeze Film Damper and Its Application to Vibration Control of Rotor System

1999 ◽  
Vol 122 (1) ◽  
pp. 7-11 ◽  
Author(s):  
Yao Guozhi ◽  
Yap Fook Fah ◽  
Chen Guang ◽  
Meng Guang ◽  
Fang Tong ◽  
...  
Keyword(s):  
Vibration Control ◽  
Large Amplitude ◽  
Critical Speed ◽  
Reynolds Equation ◽  
Control Method ◽  
Rotor System ◽  
Squeeze Film ◽  
Squeeze Film Damper ◽  
Unbalance Response ◽  
Er Damper

In this paper, a new electro-rheological multi-layer squeeze film damper (ERMSFD in short) is designed first and the constitutional Reynolds equation is established. Then the behavior of the rotor system is analyzed, the vibration around the first critical speed is suppressed and an on/off control is proposed to control the large amplitude around the first critical speed. A control method is used to suppress the sudden unbalance response. Finally, experiments are carried out to investigate the behavior of the rotor system to prove the effectiveness of the ER damper to suppress the vibration around the critical speed and the sudden unbalance response. [S0739-3717(00)00301-9]

The Dynamic Analysis of SFD-Sliding Bearing Flexible Rotor System Based on Optimization Design

2012 ◽  
Vol 159 ◽  
pp. 355-360
Author(s):  
Ji Yan Wang ◽  
Rong Chun Guo ◽  
Xu Fei Si
Keyword(s):  
High Speed ◽  
Optimization Design ◽  
Critical Speed ◽  
Structural Parameters ◽  
Rotor System ◽  
Flexible Rotor ◽  
Optimization Analysis ◽  
Sliding Bearing ◽  
Critical Speeds ◽  
Design Variables

The paper establishes the mechanical model of SFD-sliding bearing flexible rotor system, adopting Runge-Kutta method to solve nonlinear differential equation, thus acquiring the unbalanced response curve and then gaining the first two critical speeds of the system. Meanwhile, the paper analyzes the sensitivity of the system on the first two critical speeds towards structural parameters, offering design variables to optimization analysis. Based on sensitivity analysis, genetic algorithm is employed to give an optimization analysis on critical speed, which aims to remove critical speed from working speed as much as possible. The critical speed ameliorates after the optimization which supplies theoretical basis as well as theoretical analysis towards the dynamic stability of high-speed rotor system and provides reference for the design of such rotor system.

scholarly journals The Influence of Shaft’s Bending on the Coupling Vibration of a Flexible Blade-Rotor System

2017 ◽  
Vol 2017 ◽  
pp. 1-19 ◽  
Author(s):  
Chao-feng Li ◽  
Hou-xin She ◽  
Wen Liu ◽  
Bang-chun Wen
Keyword(s):  
Natural Frequency ◽  
Critical Speed ◽  
Vibration Mode ◽  
Rotor System ◽  
Rotor Blades ◽  
Mode Shapes ◽  
Coupling Vibration ◽  
Mode Function ◽  
Coupling Mode ◽  
Supporting Condition

The influence of shaft bending on the coupling vibration of rotor-blades system is nonignorable. Therefore, this paper analyzed the influence of shaft bending on the coupling vibration of rotor-blades system. The vibration mode function of shaft under elastic supporting condition was also derived to ensure accuracy of the model as well. The influence of the number of blades, the position of disk, and the support stiffness of shaft on critical speed of system was analyzed. The numerical results show that there were two categories of coupling mode shapes which belong to a set where the blade’s first two modes predominate in the system: shaft-blade (SB) mode and interblade (BB) mode due to the coupling between blade and shaft. The BB mode was of repeated frequencies of (Nb-2) multiplicity for number blades, and the SB mode was of repeated frequencies of (2) multiplicity for number blades. What is more, with the increase of the number of blades, natural frequency of rotor was decreasing linearly, that of BB mode was constant, and that of SB mode was increasing linearly. Natural frequency of BB mode was not affected while that of rotor and SB mode was affected (changed symmetrically with the center of shaft) by the position of disk. In the end, vibration characteristics of coupling mode shapes were analyzed.

Unbalance response of a magnetic suspended dual-rotor system

2019 ◽  
Vol 233 (15) ◽  
pp. 5758-5772
Author(s):  
Dongxiong Wang ◽  
Nianxian Wang ◽  
Kuisheng Chen
Keyword(s):  
Magnetic Bearing ◽  
Rotor System ◽  
Magnetic Bearings ◽  
Active Magnetic Bearing ◽  
Active Magnetic Bearings ◽  
Maximum Displacement ◽  
Critical Speeds ◽  
Unbalance Response ◽  
Rotor Imbalance ◽  
Aero Engine

The magnetic suspended dual-rotor system applied in more electric aero-engine can eliminate the wear and lubrication system of mechanical bearings and solve the vibration control issue of system effectively, which provides the possibility to improve the performance of aero-engine significantly. This research focuses on the unbalance response of the magnetic suspended dual-rotor system. First, a structure of dual-rotor system supported by two active magnetic bearings and two permanent magnetic bearings is presented. With proportional derivative (PD) control adopted, the bearing characteristics of active magnetic bearings are modeled as the equivalent stiffness and equivalent damping, and the permanent magnetic bearings are modeled as elastic support. Then, the Riccati transfer matrix method with good numerical stability is used to establish the model of the magnetic suspended dual-rotor system unbalance response. Subsequently, the validity of the present formulation has been tested against some known results available in literature and the simulation results obtained by finite element method (FEM). Finally, the dynamic characteristics of the unbalance response are investigated. The results reveal that the influence of the inner rotor imbalance excitation on the magnetic suspended dual-rotor system unbalance response is much larger than that of the outer rotor imbalance excitation. In addition, the critical speeds increase with the proportional coefficient, and the derivative coefficient can affect the amplitudes of the unbalance response, but not critical speeds. From the perspectives of the maximum bearing capacity and maximum displacement of active magnetic bearing-rotor system, the possibility of the magnetic suspended dual-rotor system safely crossing the critical speeds of the first three orders is investigated.

Effect of Temperature Distribution on Critical Speeds of a Dual-Rotor System

2014 ◽  
Vol 709 ◽  
pp. 21-24
Author(s):  
Gui Yu Xin ◽  
Ke Ming Wang ◽  
Mei Jiao Qu ◽  
Tian Yin Wang
Keyword(s):  
High Pressure ◽  
Temperature Distribution ◽  
Critical Speed ◽  
Axial Direction ◽  
Calculation Model ◽  
Rotor System ◽  
Effect Of Temperature ◽  
Critical Speeds ◽  
Calculation Results ◽  
The Impact

A dual-rotor calculation model which can expand freely in the axial direction is established in this paper, and the effects of one-dimensional axial temperature distribution on critical speeds of the dual-rotor system are analyzed with finite element method. The temperature distribution of the dual-rotor system is given referring to that of similar aero-engine rotor system. Assuming that the left end temperature remains at 0 °C, and the highest temperature on the section of the high-pressure turbine disk is 0 °C, 200 °C, 400 °C, 600 °C, and 800 °C respectively, the critical speeds of the dual-rotor system are calculated, analyzed and compared. Calculation results show that, with the increase of the highest temperature of the dual-rotor system, the reduction percentage of the critical speeds increases, and the impact on the first critical speed is most obvious. When the highest temperature is 800 °C, the first critical speed of the rotor system excited by the low-pressure rotor reduces 13.13%, and that excited by the high-pressure rotor reduces 13.49%.

Investigation on Critical Speed and Vibration Mode of High Speed Grinder

2011 ◽  
Vol 42 (10) ◽  
pp. 47-54 ◽  
Author(s):  
C. H. Li ◽  
Z. R. Liu ◽  
Y. Zhou ◽  
Y. C. Ding
Keyword(s):  
High Speed ◽  
Critical Speed ◽  
Vibration Mode ◽  
Structural Parameters ◽  
Variable Cross Section ◽  
Influential Factors ◽  
Variable Cross ◽  
Tightening Force ◽  
Rotor Bearing ◽  
Bearing System

The influences of the grinder spindle's major structural parameters on its vibration mode were investigated. Based on the transfer-matrix method and taking into consideration the gyroscopic couple, the shear, the variable cross-section and other influential factors, a dynamic model was established for the multi-disk rotor of the rotor-bearing system of the grinder spindle. The critical speeds of first three orders, the modes of variation and other dynamic characteristic parameters of the grinder spindle were programmed and calculated. The influences of the axial pre-tightening force of the bearing, the span of the fulcrum bearing as well as the changes in the front and rear overhangs on the critical speed of the rotor-bearing system on the grinder spindle and their pattern of changes were analyzed. The results showed that the working speed of the spindle system is much lower than the primary critical speed and can therefore stay away the resonance range effectively.

The Dynamic Load of Inter-Shaft Bearing and its Transmission Characteristic of Complex Rotor System

2018 ◽  
Author(s):  
Huan Yu ◽  
Bo Sun ◽  
YanHong Ma ◽  
Jie Hong
Keyword(s):  
Dynamic Model ◽  
Dynamic Load ◽  
Strain Energy ◽  
Vibration Mode ◽  
Resonance State ◽  
Rotor System ◽  
Rotor Vibration ◽  
Restoring Force ◽  
Flexural Mode ◽  
Aero Engine

Aiming at the dynamic design of dual rotor of aero-engine, the dynamic model of dual rotor system was established. And then based on the simulation results of the dynamic model established above, the unbalance distribution of dual rotor and the strain energy distribution of the flexural deformation were analyzed. The results showed that the dynamic load on inter-shaft bearing is determined by the rotor vibration mode and the rotor vibration response at the position of bearing. The flexural deformation can also affect the dynamic load on inter-shaft bearing. Under the influence of elastic restoring force generated by the flexural deformation of rotors, the dynamic load on the inter-shaft bearing under flexural mode is higher than that under the rigid mode. It was found that large dynamic load may act on inter-shaft bearing even though the rotor is not operating in the resonance state. And due to the internal damping of the rotor, the large dynamic load on the inter-shaft bearing can be obviously reduced when the load transmit to other bearings via the rotor with flexural deformation.

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