Rotor Bearing System Design on Magnetic Bearings

1995 ◽  
Author(s):  
Pranabesh De Choudhury
Keyword(s):  
System Design ◽  
High Speed ◽  
Journal Bearings ◽  
Magnetic Bearings ◽  
Ball Bearings ◽  
Tilting Pad ◽  
Rotor Bearing ◽  
Multistage Centrifugal Compressor ◽  
Tilting Pad Journal Bearings ◽  
Bearing System

Abstract The rotordynamic analysis of a high speed multistage centrifugal compressor supported on radial magnetic bearings, which has been running successfully in the field for 9000 hours to date, is presented. Iterations required to achieve an acceptable rotor configuration using magnetic bearings are discussed. The results of the rotor-bearing system on standard fluid film five shoe tilting pad journal bearings are compared to the dynamics of the rotor on magnetic bearings. Correlation of the observed peak responses with those predicted on magnetic bearings is presented. The actual orbit plots and frequency plots during the coastdown of the rotor-bearing system on auxiliary ball bearings are discussed.

Dynamic Properties of Tilting-Pad Journal Bearings: Experimental and Theoretical Investigation of Frequency Effects due to Pivot Flexibility

2006 ◽  
Vol 129 (3) ◽  
pp. 865-869 ◽  
Author(s):  
Waldemar Dmochowski
Keyword(s):  
High Speed ◽  
Dynamic Properties ◽  
Three Dimensional ◽  
Journal Bearings ◽  
Operating Conditions ◽  
Damping Properties ◽  
Frequency Effects ◽  
Tilting Pad ◽  
Stiffness And Damping ◽  
Tilting Pad Journal Bearings

Tilting-pad journal bearings (TPJBs) dominate as rotor supports in high-speed rotating machinery. The paper analyzes frequency effects on the TPJB’s stiffness and damping characteristics based on experimental and theoretical investigations. The experimental investigation has been carried out on a five pad tilting-pad journal bearing of 98mm in diameter. Time domain and multifrequency excitation has been used to evaluate the dynamic coefficients. The calculated results have been obtained from a three-dimensional computer model of TPJB, which accounts for thermal effects, turbulent oil flow, and elastic effects, including that of pad flexibility. The analyzes of the TPJB’s stiffness and damping properties showed that the frequency effects on the bearing dynamic properties depend on the operating conditions and bearing design. It has been concluded that the pad inertia and pivot flexibility are behind the variations of the stiffness and damping properties with frequency of excitation.

Numerical and experimental study on dynamic characteristics of tilting-pad journal bearings considering pivot stiffness in a vertical rotor system

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Fan Zhang ◽  
Peng Yin ◽  
Yuyang Liu ◽  
Jianmei Wang
Keyword(s):  
Dynamic Characteristics ◽  
Journal Bearings ◽  
Rotor System ◽  
Obvious Effect ◽  
Content Type ◽  
Vertical Rotor ◽  
Tilting Pad ◽  
Rotor Bearing ◽  
The Stability ◽  
Tilting Pad Journal Bearings

Purpose The purpose of this paper is to study the influence of pivot stiffness on the dynamic characteristics of tilting-pad journal bearings (TPJBs) and the stability of the bearing-rotor system. Design/methodology/approach A theoretical numerical model is established, and the influences of pivot stiffness on TPJBs and a bearing-rotor system are analyzed. Then, two kinds of pivot structures with different stiffness are designed and the vibration characteristics are tested on the vertical rotor bearing test bench. Findings The pivot stiffness has an obvious effect on the dynamic characteristics of the TPJBs and the stability of the bearing-rotor system. As a result of appropriate pivot stiffness, the critical speed and the vibration amplification factor can be reduced, the logarithmic decay rate and the stability of the rotor system can be effectively increased. While the journal whirl orbit is smoother and the rubbing is obviously reduced when the bearings have flexible pivots. Originality/value The influence of pivot stiffness on TPJBs and a vertical rotor-bearing system is studied by theoretical and experimental methods.

Thermal Deformation of Pads in Tilting 5-Pad Journal Bearing

2005 ◽  
Author(s):  
S. Strzelecki ◽  
L. Kusmierz ◽  
G. Poniewaz
Keyword(s):  
High Speed ◽  
Journal Bearing ◽  
Journal Bearings ◽  
Oil Film ◽  
Tilting Pad ◽  
Drive Trains ◽  
Shaft Misalignment ◽  
Tilting Pad Journal Bearings ◽  
Turbine Drive ◽  
Oil Film Pressure

In high speed compressors and turbine drive trains, the tilting 5-pad journal bearings are applied. Tilting-pad journal bearings are good option because they have very good hydrodynamic stability at high speed and are less sensitive to load direction and shaft misalignment. The paper introduces thermo-elastic deformations of tilting 3-pad journal bearing with asymmetric support of pads and operating at the conditions of adiabatic oil film. The deformations of pads were obtained based on the oil film pressure and temperature distributions. Reynolds, energy, geometry and viscosity equations have been solved numerically on the assumption of aligned orientation of bearing and journal axis and at static equilibrium position of journal.

Experimental and Numerical Rotordynamic Analysis of a 1500 KW Turbocharger

2020 ◽  
Author(s):  
Behzad Zamanian Yazdi ◽  
Dung L. Tran ◽  
Chinmay Deshpande
Keyword(s):  
Experimental Data ◽  
Analytical Model ◽  
High Speed ◽  
Journal Bearings ◽  
Acid Gas ◽  
Test Loop ◽  
Gas Removal ◽  
Rotor Bearing ◽  
Simulation Results ◽  
Bearing System

Abstract Hydraulic turbochargers are used in sea water reverse osmosis or acid gas removal cycles to recover wasted pressure energy, decrease operating cost, and increase the overall process efficiency. This paper presents rotordynamic analysis of a large hydraulic turbocharger developed for the acid gas removal process (1500 KW output power, shaft diameter of 101 mm, and operating speed of 8,000 rpm). The hydraulic turbocharger has significant advantages when compared to a reverse running pump such as high speed, compact hydraulics, seal-less design and process lubricated bearings. Utilizing a hydraulic turbocharger in acid gas removal cycles results in a much smaller footprint and no external lubrication oil skid and support system for mechanical seals. The turbocharger rotor consists of a hydraulic turbine runner directly coupled to a pump impeller in a back-to-back arrangement. The shaft is supported in the middle by a set of rigid-walled process-lubricated journal bearings resulting in an overhung configuration (bearing span = 180 mm, rotor mass = 50 kg). For a large high-speed rotor-bearing system, the bearing load-carrying capacity and rotordynamic stability are crucial to ensure a stable performance and to avoid catastrophic failure. In the presented study, rotordynamic performance of a rotor-bearing system is evaluated analytically and experimentally. An analytical model is developed to simulate the rotordynamic performance of a shaft supported by a set of journal bearings. The analytical model simulates the rotor’s orbit in the time domain by solving the rotor’s equation of motion, and solving the transient Reynold equation for each bearing simultaneously. In addition, the model considers the effect of turbulence. An in-house test loop is developed and used to evaluate the turbocharger’s hydraulic and mechanical performance. The test loop runs on a LabView-based control system. The rotor vibration is measured by a set of eddy-current probes, oriented perpendicular to each other. The simulation results from the analytical model are compared against measured experimental data. Comparison of the simulated waterfall and bode plots with experimental data shows that the simulation results agree with the measured data for the frequency and amplitude of vibration. Moreover, the effect of turbulence on the rotordynamic performance of the hydraulic turbocharger is investigated, and it is shown that the turbulence significantly changes the rotordynamic behavior of the system.

Dynamic Properties of Tilting-Pad Journal Bearings: Experimental and Theoretical Investigation of Frequency Effects Due to Pivot Flexibility

2006 ◽  
Author(s):  
Waldemar Dmochowski
Keyword(s):  
High Speed ◽  
Dynamic Properties ◽  
Three Dimensional ◽  
Journal Bearings ◽  
Operating Conditions ◽  
Damping Properties ◽  
Frequency Effects ◽  
Tilting Pad ◽  
Stiffness And Damping ◽  
Tilting Pad Journal Bearings

Tilting-pad journal bearings (TPJB) dominate as rotor supports in high speed rotating machinery. The paper analyzes frequency effects on the TPJB’s stiffness and damping characteristics based on experimental and theoretical investigations. The experimental investigation has been carried out on a five pad tilting-pad journal bearing of 98 mm in diameter. Time domain and multifrequency excitation has been used to evaluate the dynamic coefficients. The calculated results have been obtained from a three-dimensional computer model of TPJB, which accounts for thermal effects, turbulent oil flow, and elastic effects, including that of pad flexibility. The analyzes of the TPJB’s stiffness and damping properties showed that the frequency effects on the bearing dynamic properties depend on the operating conditions and bearing design. It has been concluded that the pad inertia and pivot flexibility are behind the variations of the stiffness and damping properties with frequency of excitation.

Frequency Effects on Dynamic Characteristics of Tilting-Pad Journal Bearings due to Pivot Flexibility

2017 ◽  
Author(s):  
Tian Jiale ◽  
Yu Lie ◽  
Zhou Jian
Keyword(s):  
Dynamic Characteristics ◽  
High Speed ◽  
Dynamic Performance ◽  
Journal Bearings ◽  
Dynamic Coefficients ◽  
Stability Performance ◽  
Limit Value ◽  
Tilting Pad ◽  
Perturbation Frequency ◽  
Tilting Pad Journal Bearings

The stable working condition of high speed, heavy loaded rotating machinery depends strongly on the stability provided by the journal bearing. Tilting pad journal bearings (TPJB) are widely used under such situation due to their inherent stability performance. However, because of the complexity of the TPJB structure, obtaining a reliable prediction of the journal bearing’s dynamic characteristics has always been a challenging task. In this paper, a theoretical analysis has been done to investigate the dynamic performance of a 4 pad TPJB with ball-in-socket pivot, emphasizing on the frequency dependency due to pivot flexibility. The analytical model containing the complete set of dynamic coefficients of the TPJB is built and the pivot stiffness is calculated and used to evaluate the equivalent dynamic coefficients of the bearing. In general, at lower perturbation frequency, the equivalent stiffness and damping increase with frequency. While for higher perturbation frequency, the dynamic coefficients are nearly independent of the frequency. Moreover, the results also show the limit value of the dynamic characteristics of the TPJB when the perturbation frequency is set to 0+ and ∞.

Efficient Models of Three-Dimensional Tilting Pad Journal Bearings for the Study of the Interactions Between Rotor and Lubricant Supply Plant

2016 ◽  
Vol 11 (1) ◽  
Author(s):  
Andrea Rindi ◽  
Stefano Rossin ◽  
R. Conti ◽  
A. Frilli ◽  
E. Galardi ◽  
...  
Keyword(s):  
High Speed ◽  
Degrees Of Freedom ◽  
Three Dimensional ◽  
3D Models ◽  
Industrial Applications ◽  
Journal Bearings ◽  
Research Activity ◽  
Steady State Condition ◽  
Tilting Pad ◽  
Tilting Pad Journal Bearings

In many industrial applications, tilting pad journal bearings (TPJBs) are increasingly used because they are very suitable both for high-speed and high external loads. Their study is fundamental in rotating machines and a compromise between accuracy and numerical efficiency is mandatory to achieve reliable results in a reasonable time. This paper mainly focuses on the development of efficient three-dimensional (3D) models of TPJBs, in order to contemporaneously describe both the rotor dynamics of the system and the lubricant supply plant in long simulations (from the initial transient phase to the steady-state condition). Usually, these two aspects are studied separately, but their interactions must be considered if an accurate description of the whole system is needed. The proposed model architecture considers all the six degrees-of-freedom (DOFs) between supporting structures and rotors and can be applied to different types of TJPB layout with different lubricant supply plants. In this research activity, the whole model has been developed and validated in collaboration with Nuovo Pignone General Electric S.p.a. which provided the required technical and experimental data.

Optimization of Tilting-Pad Journal Bearings for Integrally Geared Compressors

2015 ◽  
Author(s):  
Nico Havlik ◽  
Michael Lutz
Keyword(s):  
High Speed ◽  
Journal Bearings ◽  
Gravity Force ◽  
Power Losses ◽  
Tilting Pad ◽  
Compressor Design ◽  
Overall Efficiency ◽  
Bearing Design ◽  
Tilting Pad Journal Bearings ◽  
Highly Loaded

Tilting-pad journal bearings (TPJBs) support highly loaded high speed rotors with high requirements on rotordynamic behavior. Typical applications therefore are integrally geared compressors, where the gear force of the high speed pinions (HSPs) is at least one magnitude higher than the gravity force. A continuously rising demand for increasing the overall efficiency of integrally geared compressors leads to a necessity to expand TPJBs operation limits. Allowable limits of actual bearings often result in limitations for thermodynamical compressor design. In addition, bearings generate 20% to 40% of the mechanical power losses in integrally geared compressors. Improvements in the bearing design have to be performed in order to meet the challenges of rising loads and speeds. This paper presents an optimization of TPJBs for integrally geared compressors to meet the further demand of higher operation limits.

Suppression of Rotor-Bearing System Vibrations Through Flexible Bearing Support Damping

1976 ◽  
Vol 98 (3) ◽  
pp. 1053-1061
Author(s):  
J. M. Tessarzik ◽  
T. Chiang ◽  
R. H. Badgley
Keyword(s):  
High Speed ◽  
Journal Bearing ◽  
Amplitude Distribution ◽  
Random Vibrations ◽  
Response Characteristics ◽  
Response Data ◽  
Power Spectral ◽  
Tilting Pad ◽  
Rotor Bearing ◽  
Bearing System

A bearing damper, operating on the support flexure of a pivoted pad in a tilting-pad type gas-lubricated journal bearing, has been designed, built, and tested under externally applied random vibrations. A 36,000 rpm, 10 Kwe turbogenerator had previously been subjected to external random vibrations, and vibration response data had been recorded and analyzed for amplitude distribution and frequency content at a number of locations in the machine. Based upon data from that evaluation, a piston-type damper was designed and developed for each of the two flexibly-supported journal bearing pads (one in each of the two three-pad bearings). A modified turbogenerator, with dampers installed, has been retested under random vibration conditions. Root-mean-square vibration amplitudes were determined from the test data, and displacement power spectral density analyses have been performed. Results of these data reduction efforts have been compared with vibration tolerance limits and previously reported response characteristics of the unmodified machine. Results of the tests indicate significant reductions in vibration levels in the bearing gas-lubricant films, particularly in the rigidly mounted pads. The utility of the gas-lubricated damper for limiting rotor-bearing system vibrations in high-speed turbomachinery has thus been demonstrated.

The Subsynchronous Dynamic Behavior of Tilting-Pad Journal Bearings

1992 ◽  
Vol 114 (1) ◽  
pp. 167-173 ◽  
Author(s):  
M. F. White ◽  
S. H. Chan
Keyword(s):  
High Speed ◽  
Dynamic Stiffness ◽  
Journal Bearings ◽  
Frequency Effect ◽  
Tilting Pad ◽  
Dimensional Finite Element ◽  
The Stability ◽  
Element Technique ◽  
Tilting Pad Journal Bearing ◽  
Tilting Pad Journal Bearings

Tilting-pad journal bearings are being increasingly used to avoid bearing instability problems. This paper describes the theory and results from a design program which has been developed for tilting-pad journal bearing calculations. The present approach is based on the numerical solution of the Reynolds equation using a one-dimensional finite element technique which considers temperature and viscosity changes and can also take into account the effect of turbulent flow. Computed results of dynamic stiffness and damping coefficients show very good agreement with data from the literature. The effects of various factors which may influence the bearing dynamic characteristics are discussed. For bearings with small preloads and operating at high Sommerfeld numbers, the effective damping at subsynchronous frequencies is considerably lower than that predicted for synchronous vibration. The stiffness is also affected by frequency. This frequency effect is attenuated by increased bearing preloads and offsets. Such factors have important consequences on the stability of high speed turbomachinery supported by tilting-pad journal bearings.

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