Paper 8: An Experimental Investigation of the Floating-Pad Journal Bearing

1969 ◽  
Vol 184 (12) ◽  
pp. 54-59
Author(s):  
R. B. Howarth
Keyword(s):  
Experimental Investigation ◽  
High Speed ◽  
Journal Bearing ◽  
Load Capacity ◽  
Excited Vibration ◽  
Low Load ◽  
Static Performance

This paper describes an experimental investigation into the static performance of a floating-pad journal bearing with four pads. Up to moderate eccentricities the test bearing was found to have a somewhat greater load capacity than an equivalent plain journal bearing, and there was no evidence of instability. The geometry of the bearing also allows high lubricant flows to be used for cooling purposes without requiring excessive supply pressures. Some difficulties were experienced with starting under load and with a self-excited vibration which occurred at moderate to high eccentricities. The results of the investigation suggest that this form of bearing is most suitable for low-load, high-speed applications.

Paper 9: A Theoretical Analysis of the Floating-Pad Journal Bearing

1969 ◽  
Vol 184 (12) ◽  
pp. 60-69
Author(s):  
R. B. Howarth
Keyword(s):  
Energy Dissipation ◽  
Theoretical Analysis ◽  
High Speed ◽  
Journal Bearing ◽  
Low Energy ◽  
Rigorous Analysis ◽  
Simplified Approach ◽  
Lubricant Flow ◽  
Excited Vibration ◽  
Low Load

Limited applications and investigations have shown that the floating-pad journal bearing is a practical form of bearing which can be used to advantage. The operational complexities make a rigorous analysis exceedingly difficult if not impossible, and a simplified approach is adopted. The results of the analysis suggest that the floating-pad journal bearing is most suitable for high-speed, low-load applications where advantage can be taken of its desirable properties, in particular low energy dissipation and the high lubricant flow that can be accommodated for cooling purposes. The analysis also predicts the occurrence of a self-excited vibration becoming more pronounced as the eccentricity increases.

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.

Experimental Investigation on Cavitation Characteristics of a Three-Groove Journal Bearing

2013 ◽  
Vol 420 ◽  
pp. 47-50
Author(s):  
Ying Yang ◽  
Jing Hua Dai
Keyword(s):  
Experimental Investigation ◽  
High Speed ◽  
Journal Bearing ◽  
Rupture Zone ◽  
Work Characteristics ◽  
Oil Film ◽  
Rotating Speed ◽  
Clear Effect ◽  
Supply Pressure

Under high and super-high speed, oil film of the journal bearing is easy to crack and then becomes cavitation. The existence of cavitation has an important effect on the work characteristics of the shaft. On the journal bearing experiment rig the cavitation characteristics of the three-groove journal beaing were studied. The influences of the shaft rotating speed and supply pressure on cavitation shape were investigated. The results show that rotating speed and supply pressure have a clear effect on the cavitation shape, and the number of cavitation strip in the rupture zone decreases when the supply pressure increases.

scholarly journals A Novel Stick-Slip Nanopositioning Stage Integrated with a Flexure Hinge-Based Friction Force Adjusting Structure

Micromachines ◽  
2020 ◽  
Vol 11 (8) ◽  
pp. 765
Author(s):  
Junhui Zhu ◽  
Peng Pan ◽  
Yong Wang ◽  
Sen Gu ◽  
Rongan Zhai ◽  
...  
Keyword(s):  
Friction Force ◽  
High Speed ◽  
Simulation Analysis ◽  
Load Capacity ◽  
Dynamic Performance ◽  
Critical Role ◽  
Vertical Direction ◽  
Flexure Hinge ◽  
Stick Slip ◽  
Static Performance

The piezoelectrically-actuated stick-slip nanopositioning stage (PASSNS) has been applied extensively, and many designs of PASSNSs have been developed. The friction force between the stick-slip surfaces plays a critical role in successful movement of the stage, which influences the load capacity, dynamic performance, and positioning accuracy of the PASSNS. Toward solving the influence problems of friction force, this paper presents a novel stick-slip nanopositioning stage where the flexure hinge-based friction force adjusting unit was employed. Numerical analysis was conducted to estimate the static performance of the stage, a dynamic model was established, and simulation analysis was performed to study the dynamic performance of the stage. Further, a prototype was manufactured and a series of experiments were carried out to test the performance of the stage. The results show that the maximum forward and backward movement speeds of the stage are 1 and 0.7 mm/s, respectively, and the minimum forward and backward step displacements are approximately 11 and 12 nm, respectively. Compared to the step displacement under no working load, the forward and backward step displacements only increase by 6% and 8% with a working load of 20 g, respectively. And the load capacity of the PASSNS in the vertical direction is about 72 g. The experimental results confirm the feasibility of the proposed stage, and high accuracy, high speed, and good robustness to varying loads were achieved. These results demonstrate the great potential of the developed stage in many nanopositioning applications.

Effect of misalignment and rarefaction effect on the comprehensive characteristic of MEMS gas bearing

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Liangliang Li ◽  
Yonghui Xie
Keyword(s):  
Peer Review ◽  
High Speed ◽  
Rarefied Gas ◽  
Load Capacity ◽  
Content Type ◽  
Rarefaction Effect ◽  
Comprehensive Performance ◽  
Static Performance ◽  
The Stability ◽  
Gas Bearing

Purpose Owing to the development of the smaller-sized rotational machinery, the demand for the high-speed and low-resistance gas bearing increases rapidly. The research of micro gas bearing in the condition of rarefied gas state is still not satisfied. Therefore, the purpose of this paper is to present a numerical investigation of the effect of misalignment and rarefaction effect on the comprehensive performance of micro-electrical-mechanical system (MEMS) gas bearing. Design/methodology/approach The Fukui and Kaneko model is expanded to 2D solution domain to describe the flow field parameters. The finite element method is used to discretize the equation. Newton–Raphson method is used to solve the nonlinear equations for the static performance of gas bearing, and partial deviation method is adopted for the solution of dynamic equations. Findings The static and dynamic characteristics of MEMS gas bearing are calculated, and the comparison is made to study the influence of rarefaction effect and misalignment. The results show that the rarefaction effect will decrease bearing load capacity compared with traditional solution of Reynolds equation, and the misalignment will reduce the stability of bearing. The influence of misalignment on gas film thickness is also analyzed in this paper. Originality/value The investigation of this paper emerges the change regularity of comprehensive performance of MEMS gas bearing considering rarefaction effect and misalignment, which provides a reference for the actual manufacturing of MEMS gas bearing and for the safety operation of micro dynamic machinery. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-01-2020-0023/

Analysis of Hybrid (Hydrodynamic/Hydrostatic) Journal Bearing

2013 ◽  
Vol 650 ◽  
pp. 385-390 ◽  
Author(s):  
Vijay Kumar Dwivedi ◽  
Satish Chand ◽  
K.N. Pandey
Keyword(s):  
Finite Difference ◽  
Finite Difference Method ◽  
Difference Method ◽  
Gas Turbines ◽  
High Speed ◽  
Reynolds Equation ◽  
Journal Bearing ◽  
Load Capacity ◽  
Natural Boundary Condition ◽  
Dimensional Solution

The Hybrid (hydrodynamic/ hydrostatic) journal bearing system has found wide spread application in high speed rotating machines such as compressors, gas turbines, steam turbines, etc. The present studies include solution of Reynolds equation for hydrodynamic journal bearing with infinitely long approximation (ILA), infinitely short bearing approximation (ISA) and finite journal bearing approximation. Further Finite Journal bearing approximation considers two dimensional solution of Reynolds equation with natural boundary condition, which cannot be solved by analytical method. So, here the solutions for finite journal bearing have been done with finite difference method (a MATLAB® code is prepared for finite difference method) to get bearing performance parameters such as load capacity, Sommerfeld no., etc.

An Experimental Investigation Into the Thermohydrodynamic Behavior of a High Speed Cylindrical Bore Journal Bearing

1985 ◽  
Vol 107 (4) ◽  
pp. 538-543 ◽  
Author(s):  
D. T. Gethin ◽  
J. O. Medwell
Keyword(s):  
High Speed ◽  
Journal Bearing ◽  
Load Capacity ◽  
Transitional Flow ◽  
Outlet Temperature ◽  
Test Apparatus ◽  
Supportive Evidence ◽  
Design Procedures ◽  
Cylindrical Bore ◽  
Complex Temperature

A description of the design of a high speed journal bearing test apparatus and some results recorded from a cylindrical bore bush fed by two axial grooves are presented. These highlight the complex temperature patterns which are generated in the bush. To compliment this detailed information, the variation of load capacity, bush torque reaction, leakage, and bulk outlet temperature with speed are presented also. The work suggests that Taylor’s criterion may be applied broadly to determine the onset of non laminar flow in bearings. It also provides supportive evidence concerning the applicability of design procedures used in the transitional flow regime.

Thermohydrodynamic Analysis of Journal Bearing Operating Under Nanolubricants

2011 ◽  
Author(s):  
K. Prabhakaran Nair ◽  
P. K. Rajendra Kumar ◽  
K. Sreedhar Babu
Keyword(s):  
Journal Bearing ◽  
Numerical Technique ◽  
Load Capacity ◽  
Performance Characteristics ◽  
Nano Particles ◽  
Engine Oil ◽  
Al2o3 Nanoparticles ◽  
Static Performance ◽  
Energy Equations ◽  
Commercial Lubricant

The static performance characteristics of thermo hydrodynamic journal bearing operating under lubricant Veedol SAE 15W 40 multi grade engine oil with CuO, CeO2 and Al2O3 nanoparticles are presented. These static performance characteristics mainly depend on the viscosity of the lubricant. The addition of nano particles on commercially available lubricant may enhance the viscosity of lubricant and in turn changes the performance characteristics. In the proposed work CuO, CeO2 and Al2O3 nano particles are used with commercial lubricant Veedol SAE 15W 40 multi grade engine oil. To obtain pressure and temperature distribution, modified Reynolds and energy equations are used and these equations are solved by using the powerful numerical technique, Finite Element Method. An iterative procedure is used to establish the film extent. The static performance characteristics in terms of load capacity, attitude angle, end leakage and friction force are evaluated when the bearing operates under nanolubricants for the following cases. 1. Isoviscous; 2. Thermoviscous.

FDM Based Analysis of Gas Lubricated Foil Journal Bearing

2009 ◽  
Author(s):  
Nikita Makwana
Keyword(s):  
High Speed ◽  
Load Capacity ◽  
Differential Method ◽  
Operating Characteristics ◽  
Computing Environment ◽  
Hydrodynamic Analysis ◽  
Foil Bearing ◽  
Minimum Film Thickness ◽  
Static Performance ◽  
Gas Bearing

This article deals with the finite differential method of static performance of a foil journal gas bearing. A foil bearing is a self acting hydrodynamic device, which separates stationary and rotating components of high speed rotating machinery by a fluid film of air or other gaseous lubricant. The present work concentrates on common approach in foil bearing in calculating the carrying capacity for a given shaft position (figure-1). During this work the external load is fixed and related shaft position is investigated. For steady operating characteristics such as minimum film thickness and load capacity predicted for the foil bearing. The system of governing equation is solved numerically with FDM by a computer program written in the MATLAB computing environment. A generalized hydrodynamic analysis is conducted to systematically analyses the effect like bearing speed is discussed.

Advancements in the Performance of Aerodynamic Foil Journal Bearings: High Speed and Load Capability

1994 ◽  
Vol 116 (2) ◽  
pp. 287-294 ◽  
Author(s):  
H. Heshmat
Keyword(s):  
High Speed ◽  
Room Temperature ◽  
Journal Bearing ◽  
Load Capacity ◽  
Ambient Pressure ◽  
Journal Bearings ◽  
Test Results ◽  
Rotor Speed ◽  
Turbine Wheel ◽  
Dynamic Analyses

An advanced-design, aerodynamic, air-lubricated foil journal bearing achieved a landmark speed of 2200 cps (132,000 rpm) and a major breakthrough in load performance of 673.5 kPa (97.7 psi). At 20°C (68°F) room temperature, normal ambient pressure, 995 cps (59,700 rpm) rotor speed, and with bearing projected pad area of 1081 mm2 (1.675 in2), the bearing demonstrated a load capacity of 727.8 N (163.6 lb). The bearing also exhibited low heat generation, with about 40°C (104°F) average side leakage temperature rise. For this demonstration, a highspeed spindle utilizing a pair of 35-mm (1.375-in.) bearings and supporting a test rotor with a mass of 1.545 kg (weighing 3.41 lb) and overall length of 211 mm (8.3 in.) was successfully taken to the limiting speed of the test apparatus. This speed was set by the maximum sound velocity (Mach 1) in the spindle’s turbine wheel. The rotor/bearing speed of 4.62 × 106 DN is beyond the capability of any advanced oil-lubricated ball bearings or conventional gas-lubricated bearings. The net result is a highly stable bearing at high operating speed. This paper presents the development of this air-lubricated foil journal bearing, the operational procedures used during testing, test results (dynamic analyses), and load performance characteristics.

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