Thermal effects in the tilting pad journal bearings

Brockwell, K.; Dmochowski, Waldemar

doi:10.1088/0022-3727/25/3/008

Cited by 18 publications

(5 citation statements)

References 7 publications

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“…The static equilibrium position was influenced by nonlinear interaction between the fluid film, pad flexibility, and flexibility of the pad pivot. Subsequent models [12,13,14] were considered more accurate with the inclusion of the flexibility of the pad pivot and the pad itself. Additionally, Fillon et al…”

mentioning

confidence: 99%

Influence of Injection Pressure on the Thermohydrodynamic Behavior of Tilting Pad Journal Bearings—Model and Experiment

Bizarre

Daniel

Santos

et al. 2021

Tribology Transactions

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In rotating machines, tilting pad bearings (TPJBs) are widely used due to their enhanced design stability in comparison with alternative bearing configurations.In the present research, a thermohydrodynamic (THD) lubrication model for a tilting pad bearing with injection is developed. Within the THD lubrication model, the lubricant is also fed into each pad through a central injection orifice.The effects on the lubricant oil film pressures and temperatures and subsequent influences on the system dynamic behavior were investigated. Another important factor considered within the THD model is associated with the flexibility of the pivot of each pad and its impact on the behavior of the bearing when subjected to direct lubricant injection. The numerical model results are compared with the measurements of the rotor equilibrium position within the bearing and the pad temperatures obtained from the test rig designed specifically for the TPJB geometry with and without central pad injection. Pad temperatures are measured before the injection orifice position and after it. Agreement between experimental and model-predicted results provides confidence in the model's ability to evaluate the dynamic behavior of the bearing and its effect on the complete system through the stiffness and damping coefficients.

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mentioning

confidence: 99%

Influence of Injection Pressure on the Thermohydrodynamic Behavior of Tilting Pad Journal Bearings—Model and Experiment

Bizarre

Daniel

Santos

et al. 2021

Tribology Transactions

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show abstract

“…Regression coefficients (β ij ) that minimize the sum of the square error (L) were estimated by fitting the model using a linear least-square method in MATLAB [37]. This means that the derivatives of Equation ( 7) with respect to each polynomial coefficient are approximated to be zero, Equation (8).…”

Section: Least-square Approximation and Measures Of Fitnessmentioning

confidence: 99%

“…Recent theoretical studies dealing with the dynamics of both fixed geometry and TPJBs use advanced modeling by taking into account many different factors. These include mechanical deformation [8][9][10], thermal effect [8,11,12], pad flexibility [13][14][15], and pivots flexibility [16][17][18]. Dimond et al [19] carried out an extensive review of the development of TPJB analysis.…”

Section: Introductionmentioning

confidence: 99%

Speed-Dependent Bearing Models for Dynamic Simulations of Vertical Rotors

Benti

Gustavsson²,

Aidanpää³

2022

Machines

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Many dynamic simulations of a rotor with a journal bearing employ non-linear fluid-film lubrication models and calculate the bearing coefficients at each time step. However, calculating such a simulation is tedious and computationally expensive. This paper presents a simplified dynamic simulation model of a vertical rotor with tilting pad journal bearings under constant and variable (transient) rotor spin speed. The dynamics of a four-shoes tilting pad journal bearing are predefined using polynomial equations prior to the unbalance response simulations of the rotor-bearing system. The Navier–Stokes lubrication model is solved numerically, with the bearing coefficients calculated for six different rotor speeds and nine different eccentricity amplitudes. Using a MATLAB inbuilt function (poly53), the stiffness and damping coefficients are fitted by a two-dimensional polynomial regression and the model is qualitatively evaluated for goodness-of-fit. The percentage relative error (RMSE%) is less than 10%, and the adjusted R-square () is greater than 0.99. Prior to the unbalance response simulations, the bearing parameters are defined as a function of rotor speed and journal location. The simulation models are validated with an experiment based on the displacements of the rotor and the forces acting on the bearings. Similar patterns have been observed for both simulated and measured orbits and forces. The resultant response amplitudes increase with the rotor speed and unbalanced magnitude. Both simulation and experimental results follow a similar trend, and the amplitudes agree with slight deviations. The frequency content of the responses from the simulations is similar to those from the experiments. Amplitude peaks, which are associated with the unbalance force (1 × Ω) and the number of pads (3 × Ω and 5 × Ω), appeared in the responses from both simulations and experiments. Furthermore, the suggested simulation model is found to be at least three times faster than a classical simulation procedure that used FEM to solve the Reynolds equation at each time step.

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“…Additionally, elastic effects as a result of pressure and thermal effects can also be considered, where thermoelastohydrodynamic (TEHD) models are used. Brockwell and Dmochowski [3] report that thermal effects in TPJBs may result in distortion of the shaft, individual pads, and housing, in turn giving rise to considerable changes to both pad and bearing clearance. The authors point out that these effects must be incorporated in the theoretical model especially when dealing with large-diameter bearings, or with designs that have thin flexible pads.…”

Section: Introductionmentioning

confidence: 99%

Development of a Robust Test Rig for Tilting Pad Journal Bearing Validation

2022

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Several theoretical models for predicting the performance of tilting pad journal bearings (TPJB) have been developed by the scientific community over the years. However, reliable validation of the predictions based on the theoretical models, taking into account the complexity of TPJBs, demands robustness in the design and assembly of an improved test rig. Test bench designs for testing hydrodynamic bearings must carefully consider construction details as much as possible to observe the effect from the journal bearing and, consequently, improve the predictability of its dynamical behavior. In this context, there are still relatively few test rigs in the specific literature devoted to isolating the dynamic effects from hydrodynamic bearings for analysis purposes. Therefore, a novel test rig project is described in this work, also involving the design versatility characterized by measurement feasibility in rolling-element bearings and fixed-geometry, hydrodynamic journal bearings. This test rig aims to reproduce the most diverse operating conditions in order to measure the involved physical responses and validate the different models applied to the bearings. Therefore, the bearing performance can be properly evaluated, especially when operating under critical operating conditions, thus providing important contributions to the area of lubrication and rotor dynamics.

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Thermal effects in the tilting pad journal bearings

Cited by 18 publications

References 7 publications

Influence of Injection Pressure on the Thermohydrodynamic Behavior of Tilting Pad Journal Bearings—Model and Experiment

Influence of Injection Pressure on the Thermohydrodynamic Behavior of Tilting Pad Journal Bearings—Model and Experiment

Speed-Dependent Bearing Models for Dynamic Simulations of Vertical Rotors

Development of a Robust Test Rig for Tilting Pad Journal Bearing Validation

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