Lateral Vibration Attenuation of Shafts Supported by Tilting-Pad Journal Bearing With Embedded Electromagnetic Actuators

2013 ◽  
Vol 136 (4) ◽  
Author(s):  
Henry Pizarro Viveros ◽  
Rodrigo Nicoletti
Keyword(s):  
Journal Bearing ◽  
Electromagnetic Actuators ◽  
Hydrodynamic Bearing ◽  
Rotating Speed ◽  
Tilting Pad ◽  
Load Carrying ◽  
Vibration Attenuation ◽  
Tilting Pad Journal Bearing ◽  
The Mathematical Model ◽  
Good Agreement

Hydrodynamic tilting-pad bearings with electromagnetic actuators are designed to take advantage of the load-carrying capacity of the hydrodynamic bearing together with the actuation capacity of the electromagnets. Hence, actuators can be downsized because they do not work as bearings as it is the case of magnetic bearings. In this work, one presents the numerical and experimental analysis of rotor vibration attenuation using a tilting-pad journal bearing with embedded electromagnetic actuators when proportional-derivative (PD) control is implemented. Experimental results in the frequency domain show reductions in shaft-vibration amplitude of 11% for the rotating speed of 600 rpm and 18% for the rotating speed of 1100 rpm, with good agreement of the mathematical model. The actuation capacity of the bearing in study is compared to the capacity of other active bearings in literature, showing that the present bearing is competitive in terms of specific control capacity.

scholarly journals Measured and Predicted Operating Characteristics of a Tilting-Pad Journal Bearing with Jacking-Oil Device at Hydrostatic, Hybrid, and Hydrodynamic Operation

Lubricants ◽  
2018 ◽  
Vol 6 (3) ◽  
pp. 81 ◽  
Author(s):  
Thomas Hagemann ◽  
Peter Pfeiffer ◽  
Hubert Schwarze
Keyword(s):  
Journal Bearing ◽  
Operating Characteristics ◽  
Characteristic Parameters ◽  
Tilting Pad ◽  
Load Carrying ◽  
Manufacturing Tolerances ◽  
Stationary Conditions ◽  
Lift Off ◽  
Run Up ◽  
Tilting Pad Journal Bearing

Jacking-oil pockets are applied in many journals and thrust bearing applications in order to provide a hydrostatic oil film force that ensures a wear free run-up following a successful lift-off procedure. However, all components of the jacking-oil system have to be carefully designed in order to limit costs and prevent significant disturbance of hydrodynamic operation after deactivation of lift-oil. Experimental data and predictions for a four-pad tilting-pad journal bearing in load between pivot configuration are presented. Dynamic processes of the lift-off procedure as well as characteristic parameters of stationary conditions are studied. Moreover, hydrodynamic operation and hybrid lubrication providing a combined hydrodynamic and hydrostatic pressure distribution are investigated for sliding speeds up to 20 m/s. Analyzes of lift-off procedure prove that characteristic parameters such as lift-off pressures and vertical lift displacements are considerably influenced by manufacturing tolerances and misalignments. The comparison of hydrodynamic and hybrid lubrication provides a significant increase of load carrying capacity by additional jacking-oil supply at the maximum journal speed. In summary, results of measurements and predictions correlate well for all three investigated lubrication conditions.

Investigation of the Hydrodynamic Behavior of New Construction Hydrodynamic Tilting-Pad Journal Bearing

2005 ◽  
Author(s):  
Vladas Vekteris ◽  
Vadim Mokshin
Keyword(s):  
High Stability ◽  
Journal Bearing ◽  
Complex Method ◽  
Hydrodynamic Behavior ◽  
Hydrodynamic Bearings ◽  
Hydrodynamic Bearing ◽  
Tilting Pad ◽  
New Construction ◽  
Tilting Pad Journal Bearing

The paper describes features of new construction pad-type (segmental) hydrodynamic bearing with mobile ring and results of investigations of this bearing. The researchers obtained complex method of interaction between the mobile ring and pads. Except the diagram of distribution of lubricant pressure on the surface of pad there are presented photos of the flowing lubricant in the bearing and graphs of trajectories of the rotor journal’s axis for various number of revolutions of the rotor. Presented results of investigations show high stability of new construction hydrodynamic bearings in case of big number of revolutions of the rotor. Researchers hope that new construction bearings can be successfully used in tribological systems at the mentioned condition.

Improvement and Analysis for a Gaseous Cavitation Model Applied in a Tilting-Pad Journal Bearing

2019 ◽  
Author(s):  
Aoshuang Ding ◽  
Xuesong Li ◽  
Yuhong Li
Keyword(s):  
Journal Bearing ◽  
Three Dimensional ◽  
Cavitation Model ◽  
Local Pressure ◽  
Cavitation Process ◽  
Air Volume ◽  
Tilting Pad ◽  
Sst Model ◽  
Tilting Pad Journal Bearing ◽  
Good Agreement

Abstract Considering the gaseous cavitation rate is influenced by local pressure, a transient gaseous cavitation model is developed from an equilibrium gaseous cavitation model in consideration of transient gaseous cavitation theories and the Bunsen solubility. With the shear stress transport (SST) model with low-Re correction and air backflow from the bearing outlets, the transient gaseous cavitation model is applied to the three-dimensional simulations of an entire tilting-pad journal bearing at 3000 rpm speed and under 180 kN load. The simulated bearing pressure and load are in good agreement with the experimental data, indicating that the transient gaseous cavitation model performs well in the bearing simulations. Based on the comparisons of the simulated air and dissolved air distributions between the transient and equilibrium gaseous cavitation models, the simulated cavitation process of the transient gaseous cavitation is proved to be not in equilibrium and mass transfer occur between the backflow air and oil. The purpose of building the transient gaseous cavitation model is thus met. Analyses of the air distributions indicate that high cavitation rates and low dissolution rates makes air volume a major part of the total air volume and close to the physical gaseous cavitation process.

Calculation of Stiffness and Damping Properties of Gas Bearings

1968 ◽  
Vol 90 (4) ◽  
pp. 793-803 ◽  
Author(s):  
J. W. Lund
Keyword(s):  
Static Load ◽  
Journal Bearing ◽  
Computational Method ◽  
Gas Bearings ◽  
Rotating Speed ◽  
Damping Coefficients ◽  
Tilting Pad ◽  
Stiffness And Damping ◽  
Tilting Pad Journal Bearing ◽  
Gas Bearing

The dynamic characteristics of a gas bearing can be represented by a set of spring and damping coefficients (impedances) which are functions of the static load on the bearing, the rotating speed and the whirl frequency of the journal. For a rotor supported in gas bearings, these coefficients can be used directly in a critical speed calculation or an unbalance response calculation. In addition, the coefficients can be employed in a stability investigation. The paper gives the computational method for obtaining the spring and damping coefficients and, also, describes how they are used in rotor calculations and stability studies. Numerical results are given in graphical and tabular form for a tilting pad journal bearing and a three-lobe journal bearing.

Tilting-Pad Journal Bearing in Hybrid Operation: A Numerical and Experimental Investigation

2018 ◽  
Author(s):  
Nico Buchhorn ◽  
Sebastian Kukla ◽  
Beate Bender ◽  
Marc Neumann
Keyword(s):  
Hydrostatic Pressure ◽  
Carrying Capacity ◽  
Journal Bearing ◽  
Operating Conditions ◽  
Load Carrying Capacity ◽  
Oil Supply ◽  
Hybrid Operation ◽  
Tilting Pad ◽  
Load Carrying ◽  
Tilting Pad Journal Bearing

Large turbine bearings are usually equipped with hydrostatic jacking mechanisms to separate bearing and shaft during transient start-stop procedures. They are turned off once hydrodynamic operation is reached. In some cases, under severe operating conditions, the hydrostatic oil supply is kept running although the rotor already runs in full speed. The supplied amount of jacking oil is very small compared to the regular oil supply. However, experimental data of a large tilting-pad bearing shows that this hybrid operation has a considerable impact on the load carrying capacity in terms of lower pad temperature and larger film thickness. In this paper, a theoretical investigation to analyse the effect of increased load carrying capacity of a large tilting-pad journal bearing in hybrid operation is presented. The increase is driven by three different aspects: 1) hydrostatic pressure component, 2) increase in lubricant viscosity due to the injection of cold oil, 3) decrease of temperature gradients and thus thermal pad deformation. Subject of the approach is a ø500 mm five-pad, rocker-pivot tilting-pad journal bearing in flooded lubrication mode. The experiments are carried out on the Bochum test rig for large turbine bearings. The theoretical analyses are performed with a simulation code solving the Reynolds and energy equations for the oil film and calculating the thermomechanical pad deformations simultaneously. By considering each of the three above aspects separately and in combination, their share of load increase can be assessed individually. Contrary to expectations, the results indicate that the increase is not mostly based on the hydrostatic pressure component. Instead, the advantageously decreased pad deformations make the largest contribution to the increased load carrying capacity while the alteration in viscosity shows the least impact.

The Influence of Pad Flexibility on the Dynamic Coefficients of a Tilting Pad Journal Bearing

1987 ◽  
Vol 109 (1) ◽  
pp. 65-70 ◽  
Author(s):  
Jorgen W. Lund ◽  
Lars Bo Pedersen
Keyword(s):  
Approximate Method ◽  
Small Amplitude ◽  
Journal Bearing ◽  
Damping Properties ◽  
Dynamic Coefficients ◽  
Tilting Pad ◽  
Hydrodynamic Solution ◽  
Stiffness And Damping ◽  
Tilting Pad Journal Bearing ◽  
Good Agreement

An approximate method is developed to include the flexibility of the pad in the calculation of the stiffness and damping properties of a tilting pad journal bearing. It is a small-amplitude perturbation solution in which the pad deformation is accounted for solely by the change in clearance. A comparison of results with those obtained from a more complete elasto-hydrodynamic solution shows good agreement.

scholarly journals Part II—Case Studies for a Synchronous Thermal Instability Operating in Overhung Rotors

2004 ◽  
Vol 10 (6) ◽  
pp. 477-487 ◽  
Author(s):  
A. C. Balbahadur ◽  
R. G. Kirk
Keyword(s):  
Theoretical Model ◽  
Case Studies ◽  
Thermal Instability ◽  
Journal Bearing ◽  
Computer Programs ◽  
Tilting Pad ◽  
Theoretical Predictions ◽  
Overhung Rotors ◽  
Tilting Pad Journal Bearing ◽  
Good Agreement

In Part I, a theoretical model was developed for a synchronous thermal instability that is caused by differential viscous shearing in bearings of overhung rotors. This second part used computer programs, which were based on the theoretical model, to examine various case studies that pertain to this thermal instability. Both plain and tilting pad journal bearing rotors were examined and good agreement was found between the theoretical predictions and the practical results.

Cooling Effect and Dynamic Characteristics of Oil Film of Partial Tilting Pad Bearing

2007 ◽  
Author(s):  
Kyung-Bo Bang ◽  
Jeong-Hun Kim ◽  
Cheol-Hong Kim
Keyword(s):  
Dynamic Characteristics ◽  
Journal Bearing ◽  
Hydrodynamic Pressure ◽  
Oil Film ◽  
Rotating Speed ◽  
Damping Coefficients ◽  
Tilting Pad ◽  
Oil Flow ◽  
Stiffness And Damping ◽  
Tilting Pad Journal Bearing

In the present paper, we suggest a new type of tilting pad journal bearing to decrease oil film temperature and eliminate pad fluttering during operation. This bearing consists of tilting pad journal bearing at low casing and fixed arc type journal bearing at upper casing. Namely we changed a tilting pad bearing with a fixed arc type bearing at upper casing. To investigate the effects of changing the bearing shape, the static and dynamic characteristics were compared experimentally with conventional tilting pad journal bearing. For the static characteristics, oil film temperature, hydrodynamic pressure and oil film thickness were measured with the variation of rotating speed, bearing load and oil flow rate. The stiffness and damping coefficients of oil film were also obtained using the response subjected to harmonic external force to evaluating the dynamic characteristics. The results show that the suggested type of bearing has effect on reducing oil film temperature and increasing stiffness and damping coefficients of oil film.

A Thermohydrodynamic Analysis of Large Tilting-Pad Journal Bearing in Laminar and Turbulent Flow Regimes With Mixing

1990 ◽  
Vol 112 (3) ◽  
pp. 542-548 ◽  
Author(s):  
S. Taniguchi ◽  
T. Makino ◽  
K. Takeshita ◽  
T. Ichimura
Keyword(s):  
Turbulent Flow ◽  
Flow Model ◽  
Journal Bearing ◽  
Three Dimensional ◽  
Flow Regimes ◽  
Inlet Temperature ◽  
Tilting Pad ◽  
Laminar And Turbulent Flow ◽  
Tilting Pad Journal Bearing ◽  
Good Agreement

This paper describes a thermohydrodynamic analysis of the 19 in. diameter tilting-pad journal bearing for steam turbine in comparison with experimental data. The three-dimensional thermohydrodynamic analysis is performed in both laminar and turbulent flow regimes considering mixing inlet temperature. The linearized turbulent flow model derived by Ng and Pan (1965) is applied. Generally good agreement is obtained for bearing surface temperatures, frictional losses, and minimum film thicknesses between the theoretical and experimental results.

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