Analysis of Tilting Pad Journal Bearings With Heat Transfer Effects

1988 ◽  
Vol 110 (1) ◽  
pp. 128-133 ◽  
Author(s):  
J. D. Knight ◽  
L. E. Barrett
Keyword(s):  
Heat Transfer ◽  
Reynolds Equation ◽  
Pressure Profile ◽  
Journal Bearings ◽  
Solution Technique ◽  
Inlet Temperature ◽  
Tilting Pad ◽  
Turbine Bearing ◽  
Tilting Pad Journal Bearings ◽  
Sample Case

An approximate solution technique for tilting pad journal bearings is presented. The method makes use of approximations to the axial pressure profile and the temperature profiles and includes heat transfer between the film and its boundaries. A second order profile is assumed to represent the temperature distribution across the film. The classical Reynolds equation is applied, using the viscosity based on the cross-film average of temperature. The transfer of heat in the pads is modeled as purely radial conduction, and the journal surface temperature is given by a circumferential average of the film temperatures. Results of calculations are presented for a sample case representative of an industrial compressor or turbine bearing and are compared to isothermal results. The dynamic characteristics in this case are found to vary by 10 to 35 percent for a change in lubricant inlet temperature of 28°C. Temperature distributions in the lubricant and on the surfaces of the pads are given.

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.

Nonlinear Dynamic Behaviors of an Imbalance Rotor Supported on Fixed-Tilting Pad Journal Bearings

2011 ◽  
Vol 291-294 ◽  
pp. 1941-1951
Author(s):  
Xiao Bing Qi ◽  
Lei Feng ◽  
Yong Fang Zhang ◽  
Yan Jun Lu
Keyword(s):  
Pressure Distribution ◽  
Reynolds Equation ◽  
Axial Direction ◽  
Journal Bearings ◽  
Nonlinear Phenomena ◽  
Dynamic Behaviors ◽  
Oil Film ◽  
Tilting Pad ◽  
Field Dynamic ◽  
Tilting Pad Journal Bearings

Based on the unsteady Reynolds equation with Reynolds boundary, two-dimensional (2D) Reynolds equation is transformed into one-dimensional (1D) by taking the assumption of parabolic pressure distribution in axial direction in oil film field. Finite difference method was employed to solve 1D Reynolds equation, and the approximate pressure distribution was obtained in oil film field. Dynamic behaviors of a flexible rotor system with fixed-tilting pad journal bearings support were analyzed while the inertia of the pads was taken into consideration in the model. Imbalance responses of a symmetrical rotor-combination journal bearings (fixed-tilting pad journal bearings) system were investigated using Poincaré map and self-adaptive Runge-Kutta method. Numerical results reveal rich and complex nonlinear phenomena, such as periodic, quasi-periodic motion, etc.

Modeling of Flexible Tilting Pad Journal Bearings With Radial Oil Injection

2008 ◽  
Author(s):  
Asger M. Haugaard ◽  
Ilmar F. Santos
Keyword(s):  
Finite Element ◽  
Reynolds Equation ◽  
Dynamic Properties ◽  
Journal Bearings ◽  
System Of Equations ◽  
Servo Valve ◽  
Tilting Pad ◽  
Dimensional Finite Element ◽  
Oil Injection ◽  
Tilting Pad Journal Bearings

The static and dynamic properties of tilting-pad journal bearings with controllable radial oil injection are investigated. The tilting pads are modelled as flexible structures and their dynamics are described using a three dimensional finite element framework and linear elasticity. The oil film pressure and flow are considered to follow the modified Reynolds equation, which includes the contribution from controllable radial oil injection. The Reynolds equation is solved using a two dimensional finite element mesh. The rotor is considered to be rigid. The servo-valve flow is governed by a second order ordinary differential equation, where the right hand side is controlled by an electronic input signal. The constitutive flow pressure relationship of the injection nozzles is that of a fully developed laminar velocity profile and the servo-valve is introduced into the system of equations by a volume conservation consideration. The Reynolds equation is linearized with respect to displacements and velocities of the nodal degrees of freedom. When all nodal points satisfy the static equilibrium condition, the system of equations is dynamically perturbed and subsequently condensed to a 2 by 2 system, keeping only the lateral motion of the rotor. As expected, rotor stability is heavily influenced by the control parameters.

On the Simplifications for the Thermal Modeling of Tilting-Pad Journal Bearings Under Thermoelastohydrodynamic Regime

2012 ◽  
Author(s):  
Alejandro Cerda Varela ◽  
Michel Fillon ◽  
Ilmar Ferreira Santos
Keyword(s):  
Heat Transfer ◽  
Journal Bearing ◽  
Journal Bearings ◽  
Laminar Regime ◽  
Transfer Effects ◽  
Oil Film ◽  
Tilting Pad ◽  
Heat Transfer Effects ◽  
Tilting Pad Journal Bearing ◽  
Tilting Pad Journal Bearings

The relevance of calculating accurately the oil film temperature build up when modeling tilting-pad journal bearings is well established within the literature on the subject. This work studies the feasibility of using a thermal model for the tilting-pad journal bearing which includes a simplified formulation for inclusion of the heat transfer effects between oil film and pad surface. Such simplified approach becomes necessary when modeling the behavior of tilting-pad journal bearings operating on controllable lubrication regime. Three different simplified heat transfer models are tested, by comparing their results against the ones obtained from an state of the art tilting-pad journal bearing model, where the heat transfer effects are throughly implemented, as well as against some experimental results from the literature. The results obtained show that the validity of the simplified heat transfer models are strongly dependent on the Reynolds number for the oil flow in the bearing. For bearings operating in laminar regime, the decoupling of the oil film energy equation solving procedure, with no heat transfer terms included, with the pad heat conduction problem, where the oil film temperature is applied at the boundary as a Dirichlet condition, showed a good balance between quality of the results, implementation easiness and reduction in calculation time. For bearings on the upper limit of the laminar regime, the calculation of an approximated oil film temperature gradient in the radial direction, as proposed by Knight and Barrett, delivered the best results.

Elastohydrodynamics Applied to Active Tilting-Pad Journal Bearings

2010 ◽  
Vol 132 (2) ◽  
Author(s):  
Asger M. Haugaard ◽  
Ilmar F. Santos
Keyword(s):  
Finite Element ◽  
Reynolds Equation ◽  
Dynamic Properties ◽  
Flexible Structures ◽  
Journal Bearings ◽  
System Of Equations ◽  
Tilting Pad ◽  
Dimensional Finite Element ◽  
Oil Injection ◽  
Tilting Pad Journal Bearings

The static and dynamic properties of tilting-pad journal bearings with controllable radial oil injection are investigated theoretically. The tilting pads are modeled as flexible structures and their behavior is described using a three-dimensional finite element framework and linear elasticity. The oil film pressure and flow are considered to follow the modified Reynolds equation, which includes the contribution from controllable radial oil injection. The Reynolds equation is solved using a two-dimensional finite element mesh. The rotor is considered to be rigid in terms of shape and size, but lateral movement is permitted. The servovalve flow is governed by a second order ordinary differential equation, where the right hand side is controlled by an electronic input signal. The constitutive flow-pressure relationship of the injection orifices is that of a fully developed laminar velocity profile and the servovalve is introduced into the system of equations by a mass conservation consideration. The Reynolds equation is linearized with respect to displacements and velocities of the nodal degrees of freedom. When all nodal points satisfy static equilibrium, the system of equations is dynamically perturbed and subsequently condensed to a 2×2 system, keeping only the lateral motion of the rotor. As expected, bearing dynamic coefficients are heavily influenced by the control parameters and pad compliance.

A new dynamic mesh algorithm for studying the 3D transient flow field of tilting pad journal bearings

2016 ◽  
Vol 230 (12) ◽  
pp. 1470-1482 ◽  
Author(s):  
Mengxuan Li ◽  
Chaohua Gu ◽  
Xiaohong Pan ◽  
Shuiying Zheng ◽  
Qiang Li
Keyword(s):  
Flow Field ◽  
Equilibrium Position ◽  
Transient Flow ◽  
Journal Bearings ◽  
Dynamic Mesh ◽  
Static Equilibrium ◽  
Time Step ◽  
Tilting Pad ◽  
Grid Nodes ◽  
Tilting Pad Journal Bearings

A new dynamic mesh algorithm is developed in this paper to realize the three-dimensional (3D) computational fluid dynamics (CFD) method for studying the small clearance transient flow field of tilting pad journal bearings (TPJBs). It is based on a structured grid, ensuring that the total number and the topology relationship of the grid nodes remain unchanged during the dynamic mesh updating process. The displacements of the grid nodes can be precisely recalculated at every time step. The updated mesh maintains high quality and is suitable for transient calculation of large journal displacement in FLUENT. The calculation results, such as the static equilibrium position and the dynamic characteristic coefficients, are consistent with the two-dimensional (2D) solution of the Reynolds equation. Furthermore, in the process of transient analysis, under conditions in which the journal is away from the static equilibrium position, evident differences appear between linearized and transient oil film forces, indicating that the nonlinear transient calculation is more suitable for studying the rotor-bearing system.

scholarly journals Characterization of High-Power Turbomachinery Tilting Pad Journal Bearings: First Results Obtained on a Novel Test Bench

Lubricants ◽  
2018 ◽  
Vol 6 (1) ◽  
pp. 4 ◽  
Author(s):  
Enrico Ciulli ◽  
Paola Forte ◽  
Mirko Libraschi ◽  
Lorenzo Naldi ◽  
Matteo Nuti
Keyword(s):  
High Power ◽  
Test Bench ◽  
Journal Bearings ◽  
Tilting Pad ◽  
First Results ◽  
Tilting Pad Journal Bearings
Sign in / Sign up

Export Citation Format

Share Document