Stiffness and Damping Characteristics of Tilting-Pad Journal Bearings

1984 ◽  
pp. 45-64 ◽  
Author(s):  
H. Springer
Keyword(s):  
Journal Bearings ◽  
Damping Characteristics ◽  
Tilting Pad ◽  
Stiffness And Damping ◽  
Tilting Pad Journal Bearings

Dynamic Identification of 280mm Diameter Tilting Pad Journal Bearings: Test Results and Measurement Uncertainties Assessment of Different Designs

2020 ◽  
Author(s):  
Riccardo Ferraro ◽  
Alice Innocenti ◽  
Mirko Libraschi ◽  
Michele Barsanti ◽  
Enrico Ciulli ◽  
...  
Keyword(s):  
High Performance ◽  
Dynamic Properties ◽  
Journal Bearings ◽  
Turbulent Regime ◽  
Dynamic Identification ◽  
Damping Characteristics ◽  
Flexible Rotors ◽  
Tilting Pad ◽  
Stiffness And Damping ◽  
Tilting Pad Journal Bearings

Abstract Tilting pad journal bearings (TPJBs) are crucial elements in turbomachinery applications providing stiffness and damping characteristics that determine rotor system dynamic behavior. Hence, a correct design and an accurate dynamic properties prediction is fundamental for the successful industrial operation of rotating machinery. Current design trends in turbomachinery aiming at higher efficiency and power through weight optimization and higher operating speeds determine the development of large flexible rotors that are particularly important from the rotordynamic standpoint. The dynamic feasibility of this type of machine relies on bearing stiffness and damping characteristics that must be predicted with a certain level of confidence in order to increase the accuracy of the expected rotordynamic behaviour and avoid unpredicted vibration issues when rotors are operated. Furthermore, large centrifugal compressors commonly used in Liquified Natural Gas (LNG) applications make the bearings operate at very high peripheral speed where the transition from laminar to turbulent regime occurs, increasing the necessity of predictions accuracy. In this paper a test campaign on different large TPJB solutions operating in turbulent lubrication regime has been performed on a dedicated test rig designed for investigations on large size high-performance oil bearings. In the present work both static performance and dynamic identification of the tested TPJB solutions are presented and compared to numerical model predictions. The results of an uncertainty quantification, performed to validate the experimental results, are also shown.

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.

On the Frequency Dependency of Tilting-Pad Journal Bearings

2019 ◽  
Author(s):  
Laurence F. Wagner
Keyword(s):  
Journal Bearings ◽  
Operating Conditions ◽  
Experimental Investigations ◽  
Single Degree Of Freedom ◽  
Frequency Dependency ◽  
Exciting Frequency ◽  
Tilting Pad ◽  
Stiffness And Damping ◽  
Rotational Damping ◽  
Tilting Pad Journal Bearings

Abstract Controversy regarding the dynamic modeling of tilting-pad journal bearings (TPJB) has existed for years, with the question of the effective stiffness and damping properties, and the requirement for consideration of frequency dependency, being of great concern. There is a partial disconnect between the results of theoretical and many experimental investigations. This paper attempts to examine this issue in more of a macro sense; broadening the scope of the geometric and operating domains, and in turn expanding an understanding of related frequency effects. The investigation hinges on a single-pad, single degree-of-freedom (DOF) model that represents various geometries and operating conditions for a full bearing. The results clearly show that the dynamic coefficients must be dependent upon the “exciting” frequency, and that the dependency is primarily associated with the pad rotational damping.

Unbalance Response of Rotors Considering the Distributed Bearing Stiffness and Damping

1994 ◽  
Author(s):  
A. S. Sekhar ◽  
B. S. Prabhu
Keyword(s):  
Finite Element ◽  
Virtual Work ◽  
Journal Bearings ◽  
Principle Of Virtual Work ◽  
Unbalance Response ◽  
Tilting Pad ◽  
Bearing Stiffness ◽  
Element Technique ◽  
Stiffness And Damping ◽  
Tilting Pad Journal Bearings

Usually while modelling rotor-bearing systems the bearings are treated as point supports. In the present paper, using the finite element technique, the unbalance response of rotors is studied by considering distributed bearing stiffness and damping. The bearing stiffness and damping terms are derived by the principle of virtual work. Unbalance responses of rotors with bearing distributed effects are compared with the model using point supports and for different supports Viz., cylindrical journal bearings, tilting pad journal bearings, offset and three lobe journal bearings.

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.

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