An efficient quasi-3D rotordynamic and fluid dynamic model of Tilting Pad Journal Bearing

2016 ◽  
Vol 103 ◽  
pp. 449-464 ◽  
Author(s):  
R. Conti ◽  
A. Frilli ◽  
E. Galardi ◽  
E. Meli ◽  
D. Nocciolini ◽  
...  
Keyword(s):  
Dynamic Model ◽  
Journal Bearing ◽  
Fluid Dynamic ◽  
Tilting Pad ◽  
Tilting Pad Journal Bearing

Three-Dimensional Dynamic Model of TEHD Tilting-Pad Journal Bearing—Part I: Theoretical Modeling

2015 ◽  
Vol 137 (4) ◽  
Author(s):  
Junho Suh ◽  
Alan Palazzolo
Keyword(s):  
Heat Conduction ◽  
Dynamic Model ◽  
Dynamic Behavior ◽  
Journal Bearing ◽  
Three Dimensional ◽  
Physical Parameters ◽  
Tilting Pad ◽  
Fluid Film Thickness ◽  
Three Dimensional Finite Element ◽  
Tilting Pad Journal Bearing

This paper is focused on a new modeling method of three-dimensional (3D) thermo-elasto-hydro-dynamic (TEHD) cylindrical pivot tilting-pad journal bearing (TPJB). Varying viscosity Reynolds equation and 3D energy equation are coupled via lubricant temperature and viscosity relationship. Three-dimensional finite element method (FEM) is adopted for the analysis of: (1) heat conduction in shaft and bearing pad, (2) thermal deformation of shaft and pad, (3) flexible bearing pad dynamic behavior, and (4) heat conduction, convection, and viscous shearing in thin lubricant film. For the computational efficiency, modal coordinate transformation is utilized in the flexible pad dynamic model, and pad dynamic behavior is represented only by means of modal coordinate. Fluid film thickness is calculated by a newly developed node based method, where pad arbitrary thermal and elastic deformation and journal thermal expansion are taken into account simultaneously. The main goal of this research is to provide more accurate numerical TPJB model than developed before so that the designers of rotating machinery are able to understand the bearing dynamic behavior and avoid unpredicted problem by selection of physical parameters.

scholarly journals Improvement of Tilting-Pad Journal Bearing Operating Characteristics by Application of Eddy Grooves

Lubricants ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 18
Author(s):  
Eckhard Schüler ◽  
Olaf Berner
Keyword(s):  
High Speed ◽  
Journal Bearing ◽  
Load Capacity ◽  
Fluid Film ◽  
Operating Characteristics ◽  
Fluid Film Bearings ◽  
Tilting Pad ◽  
Bearing Load ◽  
Bearing Loads ◽  
Tilting Pad Journal Bearing

In high speed, high load fluid-film bearings, the laminar-turbulent flow transition can lead to a considerable reduction of the maximum bearing temperatures, due to a homogenization of the fluid-film temperature in radial direction. Since this phenomenon only occurs significantly in large bearings or at very high sliding speeds, means to achieve the effect at lower speeds have been investigated in the past. This paper shows an experimental investigation of this effect and how it can be used for smaller bearings by optimized eddy grooves, machined into the bearing surface. The investigations were carried out on a Miba journal bearing test rig with Ø120 mm shaft diameter at speeds between 50 m/s–110 m/s and at specific bearing loads up to 4.0 MPa. To investigate the potential of this technology, additional temperature probes were installed at the crucial position directly in the sliding surface of an up-to-date tilting pad journal bearing. The results show that the achieved surface temperature reduction with the optimized eddy grooves is significant and represents a considerable enhancement of bearing load capacity. This increase in performance opens new options for the design of bearings and related turbomachinery applications.

Dynamic Analysis of Tilting-Pad Journal Bearing—Influence of Pad Deformations

1994 ◽  
Vol 116 (3) ◽  
pp. 621-627 ◽  
Author(s):  
H. Desbordes ◽  
M. Fillon ◽  
C. Chan Hew Wai ◽  
J. Frene
Keyword(s):  
Film Thickness ◽  
Pressure Field ◽  
Journal Bearing ◽  
Maximum Pressure ◽  
Tilting Pad ◽  
Minimum Film Thickness ◽  
Dimensional Finite Element ◽  
The One ◽  
Tilting Pad Journal Bearing ◽  
Tilting Pad Journal Bearings

A theoretical nonlinear analysis of tilting-pad journal bearings is presented for small and large unbalance loads under isothermal conditions. The radial displacements of internal pad surface due to pressure field are determined by a two-dimensional finite element method in order to define the actual film thickness. The influence of pad deformations on the journal orbit, on the minimum film thickness and on the maximum pressure is studied. The effects of pad displacements are to decrease the minimum film thickness and to increase the maximum pressure. The orbit amplitude is also increased by 20 percent for the large unbalance load compared to the one obtained for rigid pad.

Tilting Pad Journal Bearings: A Discussion on Stability Calculation, Frequency Dependence, and Pad and Pivot Flexibility

2012 ◽  
Author(s):  
Jason C. Wilkes ◽  
Dara W. Childs
Keyword(s):  
Degrees Of Freedom ◽  
Journal Bearing ◽  
Operating Temperature ◽  
Excitation Frequency ◽  
Full Model ◽  
Stability Calculation ◽  
Damping Coefficients ◽  
Tilting Pad ◽  
Stiffness And Damping ◽  
Tilting Pad Journal Bearing

For several years, researchers have presented predictions showing that using a full tilting-pad journal bearing (TPJB) model (retaining all of the pad degrees of freedom) is necessary to accurately perform stability calculations for a shaft operating on TPJBs. This paper will discuss this issue, discuss the importance of pad and pivot flexibility in predicting impedance coefficients for the tilting-pad journal bearing, present measured changes in bearing clearance with operating temperature, and summarize the differences between measured and predicted frequency dependence of dynamic impedance coefficients. The current work presents recent test data for a 100 mm (4 in) five-pad TPJB tested in load on pad (LOP) configuration. Measured results include bearing clearance as a function of operating temperature, pad clearance and radial displacement of the loaded pad (the pad having the static load vector directed through its pivot), and frequency dependent stiffness and damping. Measured hot bearing clearances are approximately 30% smaller than measured cold bearing clearances and are inversely proportional to pad surface temperature; predicting bearing impedances with a rigid pad and pivot model using these reduced clearances results in overpredicted stiffness and damping coefficients that are several times larger than previous comparisons. The effect of employing a full bearing model versus a reduced bearing model (where only journal degrees of freedom are retained) in a stability calculation for a realistic rotor-bearing system is assessed. For the bearing tested, the bearing coefficients reduced at the frequency of the unstable eigenvalue (subsynchronously reduced) predicted a destabilizing cross-coupled stiffness coefficient at the onset of instability within 1% of the full model, while synchronously reduced coefficients for the lightly loaded bearing required 25% more destabilizing cross-coupled stiffness than the full model to cause system instability. The same stability calculation was performed using measured stiffness and damping coefficients at synchronous and subsynchronous frequencies. These predictions showed that both the synchronously measured stiffness and damping and predictions using the full bearing model were more conservative than the model using subsynchronously measured stiffness and damping, an outcome that is completely opposite from conclusions reached by comparing different prediction models. This contrasting outcome results from a predicted increase in damping with increasing excitation frequency at all speeds and loads; however, this increase in damping with increasing excitation frequency was only measured at the most heavily loaded conditions.

Experimental Determination of Dynamic Characteristics of a Full Size Gas Turbine Tilting-Pad Journal Bearing by an Impact Test Method

1991 ◽  
Author(s):  
S. H. Chan ◽  
M. F. White
Keyword(s):  
Gas Turbine ◽  
Impact Test ◽  
Journal Bearing ◽  
Estimation Procedure ◽  
Response Spectra ◽  
Test Method ◽  
Full Size ◽  
Tilting Pad ◽  
Tilting Pad Journal Bearing ◽  
The Impact

Abstract Measurements have been taken on an experimental rotor-bearing test rig which consists of a full size gas turbine shaft supported by two five-pad tilting-pad journal bearings. The impact test method was applied by exciting one end of the shaft in-situ by means of a hammer blow. Impact forces and response displacements were collected and analysed with suitable corrections for runout effect. Averaged frequency response spectra thus obtained were used in a parameter estimation procedure to calculate the dynamic coefficients of the tested tilting-pad journal bearing. An analytical single degree-of-freedom model was employed and one of the input parameters in the mechanical model, the effective mass, was found to significantly influence the estimated results. The measured stiffness and damping coefficients are compared with results predicted by a bearing design program. Possible sources of discrepancies between experimental and theoretical results are discussed.

Nonlinear Vibration Analysis of a Flexible Rotor Supported by a Flexure Pivot Tilting Pad Journal Bearing in Comparison to a Fixed Profile Journal Bearing with Experimental Verification

2021 ◽  
Author(s):  
Nuntaphong Koondilogpiboon ◽  
Tsuyoshi Inoue
Keyword(s):  
Hopf Bifurcation ◽  
Journal Bearing ◽  
Flexible Rotor ◽  
Maximum Test ◽  
Operating Region ◽  
Stable Operating ◽  
Subcritical Hopf Bifurcation ◽  
Tilting Pad ◽  
Calculation Results ◽  
Tilting Pad Journal Bearing

Abstract In this paper, an efficient numerical method consisting of the real mode component mode synthesis (CMS) model reduction, shooting method with parallel computing, and Floquet analysis was developed for nonlinear rotordynamics analysis of a flexible rotor supported by a 4-lobe flexure pivot tilting pad journal bearing (FPTPJB) in load-on-pad (LOP) and load-between-pad (LBP) orientations in comparison to a fixed profile journal bearing (JB) of the same pad geometry. The method used the rotor's finite elements and bearing forces obtained from directly solving the Reynolds equation to determine the limit cycles and Hopf bifurcation types. For the investigated rotor and bearing parameters, the numerical results indicated that the onset speed of instability (OSI) of FPTPJB is considerably higher than that of JB of the same orientation. Also, FPTPJB in LOP orientation yielded higher OSI than the LBP one, whereas the OSI of JB in LOP orientation was substantially higher than the LBP counterpart. Nonlinear calculation results indicated that all bearing types and orientations gave subcritical Hopf bifurcation. The FPTPJB in LOP orientation produced the largest stable operating region, whereas the JB in LBP configuration yield the smallest one. The experiment showed subcritical Hopf bifurcation occurred at speed close to the calculated OSI in all cases except FPTPJB in LOP orientation that the OSI is higher than the maximum test rig speed. The whirling orbit had the same frequency as the first critical speed and precessed in the direction of shaft rotation.

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