A Rotordynamic, Thermal, and Thrust Load Performance Gas Bearing Test Rig and Test Results for Tilting Pad Journal Bearings and Spiral Groove Thrust Bearings

2017 ◽  
Vol 139 (12) ◽  
Author(s):  
Aaron M. Rimpel ◽  
Giuseppe Vannini ◽  
Jongsoo Kim
Keyword(s):  
Journal Bearings ◽  
Spiral Groove ◽  
Test Rig ◽  
Radial Temperature ◽  
Gas Bearings ◽  
Thrust Bearings ◽  
Tilting Pad ◽  
Gas Bearing ◽  
Thrust Load ◽  
Tilting Pad Journal Bearings

A high-speed gas bearing test rig was developed to characterize rotordynamic, thermal, and thrust load performance of gas bearings being developed for an oil-free turboexpander. The radial bearings (RBs) tested in this paper were tilting pad journal bearings with radial compliance features that allow the bearing bore to increase to accommodate shaft growth, and the thrust bearings (TBs) were a spiral groove type with axial compliance features. The TB accounts for over 90% of the combined bearing power consumption, which has a cubic relationship with speed and increases with case pressure. RB circumferential pad temperatures increased approximately with speed to the fourth or fifth power, with slightly higher temperature rise for lower case pressure. Maximum steady-state bearing pad temperatures increase with increasing speed for similar cooling mass flow rates; however, only the TB showed a significant increase in temperature with higher case pressure. The TBs were stable at all speeds, but the load capacity was found to be lower than anticipated, apparently due to pad deformations caused by radial temperature gradients in the stator. More advanced modeling approaches have been proposed to better understand the TB thermal behavior and to improve the TB design. Finally, the RBs tested were demonstrated to be stable up to the design speed of 130 krpm, which represents the highest surface speed for tilting pad gas bearings tested in the literature.

A Rotordynamic, Thermal, and Thrust Load Performance Gas Bearing Test Rig and Test Results for Tilting Pad Journal Bearings and Spiral Groove Thrust Bearings

2016 ◽  
Author(s):  
Aaron M. Rimpel ◽  
Giuseppe Vannini ◽  
Jongsoo Kim
Keyword(s):  
Thrust Bearing ◽  
Journal Bearings ◽  
Temperature Gradients ◽  
Spiral Groove ◽  
Test Rig ◽  
Thrust Bearings ◽  
Tilting Pad ◽  
Gas Bearing ◽  
Thrust Load ◽  
Tilting Pad Journal Bearings

A high speed gas bearing test rig was developed to characterize rotordynamic, thermal, and thrust load performance of gas bearings being developed for an oil-free turboexpander. The radial bearings tested in this paper were tilting pad journal bearings with radial compliance features that allow the bearing bore to increase to accommodate shaft growth, and the thrust bearings were a spiral groove type with axial compliance features. The thrust bearing accounts for over 90% of the combined bearing power consumption, which has a cubic relationship with speed and increases with case pressure. Radial bearing circumferential pad temperature gradients increased approximately with speed to the fourth or fifth power, with slightly higher temperature rise for lower case pressure. Maximum steady state bearing pad temperatures increase with increasing speed for similar cooling mass flow rates; however, only the thrust bearing showed a significant increase in temperature with higher case pressure. The thrust bearings were stable at all speeds, but the load capacity was found to be lower than anticipated, apparently due to pad deformations caused by radial temperature gradients in the stator. More advanced modeling approaches have been proposed to better understand the thrust bearing thermal behavior and to improve the thrust bearing design. Finally, the radial bearings tested were demonstrated to be stable up to the design speed of 130 krpm, which represents the highest surface speed for tilting pad gas bearings tested in the literature.

The Influence of Ambient Pressure on the Measured Load Capacity of Bump-Foil and Spiral-Groove Gas Thrust Bearings at Ambient Pressures up to 69 Bar on a Novel High-Pressure Gas Bearing Test Rig

2019 ◽  
Author(s):  
Jason Wilkes ◽  
Ryan Cater ◽  
Erik Swanson ◽  
Kevin Passmore ◽  
Jerry Brady
Keyword(s):  
Power Loss ◽  
Thrust Bearing ◽  
Load Capacity ◽  
Ambient Pressure ◽  
Spiral Groove ◽  
Test Rig ◽  
Thrust Bearings ◽  
Order Of Magnitude ◽  
Foil Thrust Bearing ◽  
Thrust Load

Abstract This paper will show the influence of ambient pressure on the thrust capacity of bump-foil and spiral-groove gas thrust bearings. The bearings were operating in nitrogen at various pressures up to 69 bar, and were tested to failure. Failure was detected at various pressures by incrementally increasing the thrust load applied to the thrust bearing until the bearing was no longer thermally stable, or until contact was observed by a temperature spike measured by thermocouples within the bearing. These tests were performed on a novel thrust bearing test rig that was developed to allow thrust testing at pressures up to 207 bar cavity pressure at 260°C while rotating at speeds up to 120,000 rpm. The test rig floats on hydrostatic air bearings to allow for the direct measurement of applied thrust load through linkages that connect the stationary thrust loader to the rotor housing. Test results on a 65 mm (2.56 in) bump-foil thrust bearing at 100 krpm show a marked increase in load capacity with gas density, which has not previously been shown experimentally. Results also show that the load capacity of a similarly sized spiral-groove thrust bearing are relatively insensitive to pressure, and supported an order-of-magnitude less load than that observed for the bump-foil thrust bearing. These results are compared with analytical predictions, which agree reasonably with the experimental results. Predicted power loss is also presented for the bump-foil bearing; however, measured power loss was substantially higher.

Improving Tilting-Pad Journal Bearing Predictions: Part I—Model Development and Impact of Rotor-Excited Versus Bearing-Excited Impedance Coefficients

2012 ◽  
Author(s):  
Jason C. Wilkes ◽  
Dara W. Childs
Keyword(s):  
Journal Bearing ◽  
Reaction Force ◽  
Model Development ◽  
Journal Bearings ◽  
Test Rig ◽  
Tilting Pad ◽  
Force Components ◽  
Rotor Journal ◽  
Tilting Pad Journal Bearing ◽  
Tilting Pad Journal Bearings

The floating-bearing-test-rig concept was initially developed by Glienicke in 1966 and has since been used to test many tilting-pad journal bearings (TPJBs). The impedances measured during these tests have been compared to rotor/journal perturbed impedance predictions. Since the inertial acceleration of a pad is different for bearing perturbed and rotor perturbed motions, the bearing’s reaction force components for bearing perturbed and journal perturbed motions will also differ. An understanding of how bearing perturbed and rotor perturbed impedances differ is needed to assess the validity of past, present, and future comparisons between TPJB test data and predictions. A new TPJB perturbation model is developed including the effects of angular, radial, and transverse pad motion and changes in pad clearance due to pad bending compliance. Though all of these pad variables have previously been included in different analyses, there are no publications containing perturbations of all four variables. In addition, previous researchers have only perturbed the rotor, while both the bearing and rotor motions are perturbed in the present analysis. The applicability of comparing rotor-perturbed bearing impedance predictions to impedances measured on a bearing-perturbed test rig is assessed by comparing rotor perturbed and bearing perturbed impedance predictions for an example bearing.

Characterization of Five-Pad Tilting-Pad Journal Bearings Using an Original Test-Rig

2011 ◽  
Author(s):  
S. Chatterton ◽  
P. Pennacchi ◽  
A. Vania ◽  
E. Tanzi ◽  
R. Ricci
Keyword(s):  
Film Thickness ◽  
Gas Turbines ◽  
Journal Bearings ◽  
Fluid Film ◽  
Test Rig ◽  
Theoretical Evaluation ◽  
Oil Film ◽  
Tilting Pad ◽  
Fluid Film Thickness ◽  
Tilting Pad Journal Bearings

Tilting-pad journal bearings are installed with increased frequency owing to their dynamic stability characteristics in several rotating machine applications, typically in high rotating speed cases. This usually happens for new installations in highspeed compressors or during revamping operations of steam and gas turbines for power generation. The selection from a catalogue, or the design of a new bearing, requires the knowledge of the bearing characteristics such as babbitt metal temperatures, fluid-film thickness, load capacity, stiffness and damping coefficients. Temperature and fluid-film thickness are essential for the safety of the bearing. Babbitt metal is subject to creep at high temperatures, as it happens at high speed operations. On the contrary, at low speed or with high loads, oil-film thickness could be too low, resulting in metal to metal contact. Oil-film dynamic coefficients are largely responsible of the dynamic behaviour and of the stability of the rotor-tilting-pad-bearing system. Therefore, the theoretical evaluation and/or the experimental estimation of these coefficients are mandatory in the design phase. The theoretical evaluation of these coefficients for tilting pad journal bearings is difficult due to their complex geometry, boundary and thermal conditions and turbulent flow, whereas an experimental characterization requires a suitable test rig. The paper describes the test rig designed to this purpose and its unusual configuration with respect to other test rigs available in literature. Some preliminary tests performed for the bearing characterization are also shown.

Improving Tilting Pad Journal Bearing Predictions—Part I: Model Development and Impact of Rotor Excited Versus Bearing Excited Impedance Coefficients

2012 ◽  
Vol 135 (1) ◽  
Author(s):  
Jason C. Wilkes ◽  
Dara W. Childs
Keyword(s):  
Journal Bearing ◽  
Reaction Force ◽  
Model Development ◽  
Journal Bearings ◽  
Test Rig ◽  
Tilting Pad ◽  
Force Components ◽  
Rotor Journal ◽  
Tilting Pad Journal Bearing ◽  
Tilting Pad Journal Bearings

The floating-bearing-test-rig concept was initially developed by Glienicke in 1966 and has since been used to test many tilting-pad journal bearings (TPJBs). The impedances measured during these tests have been compared to rotor/journal-perturbed impedance predictions. Since the inertial acceleration of a pad is different for bearing-perturbed and rotor-perturbed motions, the bearing's reaction force components for bearing-perturbed and journal-perturbed motions will also differ. An understanding of how bearing-perturbed and rotor-perturbed impedances differ is needed to assess the validity of past, present, and future comparisons between TPJB test data and predictions. A new TPJB perturbation model is developed including the effects of angular, radial, and transverse pad motion and changes in pad clearance due to pad bending compliance. Though all of these pad variables have previously been included in different analyses, there are no publications containing perturbations of all four variables. In addition, previous researchers have only perturbed the rotor, while both the bearing and rotor motions are perturbed in the present analysis. The applicability of comparing rotor-perturbed bearing impedance predictions to impedances measured on a bearing-perturbed test rig is assessed by comparing rotor-perturbed and bearing-perturbed impedance predictions for an example bearing.

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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