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.

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.

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.

scholarly journals Cooled Pads for Tilting-Pad Journal Bearings

Lubricants ◽  
2019 ◽  
Vol 7 (10) ◽  
pp. 92
Author(s):  
Steven Chatterton ◽  
Paolo Pennacchi ◽  
Andrea Vania ◽  
Phuoc Vinh Dang
Keyword(s):  
Cross Sections ◽  
Three Dimensional ◽  
Experimental Tests ◽  
Journal Bearings ◽  
Maximum Temperature ◽  
Inlet Temperature ◽  
Oil Film ◽  
External Cooling ◽  
Tilting Pad ◽  
Tilting Pad Journal Bearings

Tilting-pad journal bearings (TPJBs) are widely installed in rotating machines owing to their high stability, but some drawbacks can be noted, such as higher cost with respect to cylindrical journal bearings and thermal issues. High temperatures in the pads correspond to low oil-film thicknesses and large thermal deformations in the pads. Therefore, the restriction of the maximum temperature of the bearing is a key aspect for oil-film bearings. The temperature reduction is generally obtained by adopting higher oil inlet flowrates or suitable oil nozzles. In this paper, the idea of using cooled pads with internal channels in which an external cooling fluid is circulated will be applied to a TPJB for the first time. The three-dimensional TEHD model of the TPJB, equipped with a cooled pad, will be introduced, and the results of the numerical simulations will be discussed. Several analyses have been performed in order to investigate the influence of cooling conditions, such as the type, flowrate, inlet temperature and number of cooled pads. Two types of pad geometry with different cross-sections of the cooling circuit, namely, circular and six-square multi-channel sections, have been compared to the reference bearing with solid pads. Simple experimental tests were performed by means of a test rig equipped with a cooled pad bearing obtained with the additive manufacturing process, thus showing the effectiveness of the solution and the agreement with the predictions.

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.

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.

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 ∞.

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.

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.

Development and Validation of an Efficient TEHD Model of Tilting Pad Journal Bearings

2016 ◽  
Author(s):  
R. Conti ◽  
A. Frilli ◽  
E. Meli ◽  
D. Nocciolini ◽  
S. Panconi ◽  
...  
Keyword(s):  
High Speed ◽  
Fluid Dynamic ◽  
Thermal Characteristics ◽  
Journal Bearings ◽  
Elastic Behaviour ◽  
Accurate Analysis ◽  
Tilting Pad ◽  
Thermal Phenomena ◽  
Physical Phenomena ◽  
Tilting Pad Journal Bearings

The large success of Tilting Pad Journal Bearings (TPJBs) for the use in high speed/high load applications is due to their intrinsic stability properties, which allow superior rotor dynamic performances. TPJBs operation involves different physical phenomena, like the pads flexibility and the heat exchange between solids and fluids: an accurate analysis of these phenomena is fundamental in order to successfully employ TPJBs. In this paper, the authors, in cooperation with General Electric Nuovo Pignone, develop an innovative 3D TPJB modelling approach that allows an accurate analysis of the interactions between the fluid dynamic and thermal phenomena with the elastic behaviour of the solid components (ThermoElastoHydroDynamic analysis). The main objective of the proposed model is to provide accurate 3D results with low computational times. The TPJB model has been also experimentally validated, focusing on the thermal characteristics of the system and the interactions due to the TEHD behaviour of the bearing system.

Nonlinear Analysis of Rotordynamic Instabilities in High-Speed Turbomachinery

1994 ◽  
Author(s):  
Dennis S. H. Chan
Keyword(s):  
High Speed ◽  
Dynamic Equilibrium ◽  
Journal Bearings ◽  
Stability Estimates ◽  
Significant Implication ◽  
Stability Margins ◽  
Mass Unbalance ◽  
Flexible Rotors ◽  
Tilting Pad ◽  
Tilting Pad Journal Bearings

A nonlinear approach based on the method of averaging has been developed to study unstable lateral vibrations of rotors in high-speed turbomachinery. The method makes use of an extended concept of bearing dynamic coefficients which are defined by applying small perturbations to the dynamic equilibrium positions. It has been applied to determine the stability threshold of flexible rotors supported on short and tilting-pad journal bearings respectively. Stability performance of systems supported on short journal bearings is improved by the presence of mass unbalance. However, for flexible rotors supported on tilting-pad journal bearings, increased unbalance can lead to lower rotordynamic stability margins. This has the significant implication that stability estimates from linear analysis are not always conservative. The present method provides a computationally more efficient way to better understand the nonlinear vibration behaviour of high-speed turbomachinery.

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