Measurements of Static Loading Versus Eccentricity in a Flexure-Pivot Tilting Pad Journal Bearing

1997 ◽  
Vol 119 (2) ◽  
pp. 297-304 ◽  
Author(s):  
Nick V. Walton ◽  
Luis San Andres
Keyword(s):  
Static Loading ◽  
Mechanical Energy ◽  
Operating Conditions ◽  
Good Prediction ◽  
Power Losses ◽  
Static Loads ◽  
Numerical Predictions ◽  
Tilting Pad ◽  
Bearing Assembly ◽  
Tilting Pad Journal Bearing

An experimental investigation examining the static loading characteristics of a four-pad, flexure-pivot tilting pad bearing is presented. Tests are conducted on a Fluid Film Bearing Element Test Rig for journal speeds ranging from 1800 to 4500 rpm, and applied static loads between pads to 1400 N. Results obtained from measurements of bearing eccentricities and bearing pad temperatures were compared to numerical predictions. Bearing power losses were also estimated using a simple thermal model for the bearing assembly. Comparisons between theory and experimental results indicate good correlation for measured eccentricities over the tested range of applied static loads and journal speeds. Negligible displacements in the direction orthogonal to the applied load verified the expected behavior of the test bearing over the range of operating conditions. Thermal analysis of the hearing system lead to good prediction of the bearing power losses, and indicated that the majority of the mechanical energy is transferred via convection.

Thermohydrodynamic Performance of a Tilting Pad Journal Bearing With Spot Lubrication

1991 ◽  
Vol 113 (3) ◽  
pp. 615-619 ◽  
Author(s):  
M. Tanaka
Keyword(s):  
High Speed ◽  
Journal Bearing ◽  
Safety Margin ◽  
Operating Conditions ◽  
New Method ◽  
Shaft Speed ◽  
Tilting Pad ◽  
Conventional Methods ◽  
Tilting Pad Journal Bearing

A new method of lubricant feeding is presented for tilting pad journal bearing and its effect on the thermohydrodynamic performance of the bearing is investigated theoretically and experimentally for various operating conditions. The new method can significantly reduce the maximum pad temperature compared with conventional methods, and its effect becomes pronounced with the increase in operating shaft speed. The method is promising for high speed journal pad bearing which is rapidly decreasing a safety margin against seizure due to the dangerously rising maximum pad temperature.

Development of an Active Control System for Rotating Machinery by Means of Tilting Pad Journal Bearings

2016 ◽  
Author(s):  
Steven Chatterton ◽  
Filippo Cangioli ◽  
Paolo Pennacchi ◽  
Andrea Vania ◽  
Phuoc Vinh Dang
Keyword(s):  
Control System ◽  
Journal Bearing ◽  
Sliding Mode ◽  
Resonance Condition ◽  
Journal Bearings ◽  
Operating Conditions ◽  
Rotating Machines ◽  
Tilting Pad ◽  
Tilting Pad Journal Bearing ◽  
Tilting Pad Journal Bearings

The current design trend of rotating machines like turbo-generators, compressors, turbines, and pumps is focused on obtaining both high dynamic performances and high versatility of machines in different operating conditions. The first target is nowadays achieved by equipping machines with tilting pad journal bearings. For the second target, State-of-the-Art researches are focused on the development of active systems able to adapt the dynamic behavior of the machine to the external environment and new operating conditions. Typical causes of large vibration in rotating machines are faults, residual unbalance, resonance condition and instabilities. Aiming at vibration reduction, in recent years many studies are carried out to investigate different solutions; one of them is based on active tilting pad journal bearing. In this paper, the authors investigate, by simulations, the reduction of shaft vibration by controlling the motion of the pads of a tilting pad journal bearing. The basic idea is to balance the exciting force on the shaft with a suitable resulting force of the oil-film pressure distribution. In particular, a sliding mode controller has been considered and both angular rotation of the pads about the pivot and the radial motion of the pivot have been analyzed. Sliding mode control guarantees high robustness of the control system in real applications that can be characterized by a strong non-linear behavior. In the paper a general consideration about the bearing, the actuating methods and the control system have been provided. A numerical analysis of large size rotor equipped with active pads has been carried out in order to verify the effectiveness of the system in several conditions, even during the most critical operating phase, i.e. the lateral critical speed.

Thrust Bearings for Power Gas Turbines

1971 ◽  
Author(s):  
A. J. Leopard
Keyword(s):  
Gas Turbines ◽  
Load Capacity ◽  
Point Of View ◽  
Power Losses ◽  
Service Experience ◽  
Thrust Bearings ◽  
Tilting Pad ◽  
Bearing Assembly ◽  
Design Requirements ◽  
New System

The design requirements of thrust bearings for power gas turbines are discussed with reference to designs which have given satisfactory service. The shortcomings of these designs are analyzed both from the point of view of efficiency and that of service experience. The development of a new system of lubrication designed to overcome these shortcomings is outlined. It is shown that this system, when applied to tilting pad thrust bearings in power turbines, can result in a simpler bearing assembly with increased load capacity and substantially ower power losses.

Partial EHL friction coefficient model to predict power losses in cylindrical gears

2018 ◽  
Vol 233 (2) ◽  
pp. 303-316 ◽  
Author(s):  
Aitor Arana ◽  
Jon Larrañaga ◽  
Ibai Ulacia
Keyword(s):  
Friction Coefficient ◽  
Operating Conditions ◽  
Power Losses ◽  
Gear Mesh ◽  
Numerical Predictions ◽  
Reference Stress ◽  
Fluid Load ◽  
Stress Behaviour ◽  
Good Agreement ◽  
Ehl Friction

The accurate prediction of friction coefficient and power losses in the gear mesh is a key subject to several gear-related fields of study. However, there is still not a unified method for large ranges of operating conditions, different gear geometries and lubricant types. The current paper meets this demand by modelling partial EHL friction with an asperity-fluid load sharing approach where fluid traction is calculated with the Ree-Eyring equation and the reference stress behaviour is predicted from piezoviscosity coefficient. It will be shown that only an accurate description of the lubricant’s viscosity behaviour is required to compute friction in gears. Finally, mesh power losses are predicted considering thermal effects and numerical predictions are compared to experimental results showing good agreement.

Experimental Study of Tilting-Pad Journal Bearings—Comparison With Theoretical Thermoelastohydrodynamic Results

1992 ◽  
Vol 114 (3) ◽  
pp. 579-587 ◽  
Author(s):  
Michel Fillon ◽  
Jean-Claude Bligoud ◽  
Jean Freˆne
Keyword(s):  
Experimental Study ◽  
Theoretical Model ◽  
Rotational Speed ◽  
Journal Bearing ◽  
Journal Bearings ◽  
Operating Conditions ◽  
Operating Characteristics ◽  
Tilting Pad ◽  
Tilting Pad Journal Bearing ◽  
Tilting Pad Journal Bearings

Operating characteristics of four-shoe tilting-pad journal bearings of 100 mm diameter and 70 mm length are determined on an experimental device. The load, between pad configuration, varies from 0 to 10,000 N and the rotational speed is up to 4000 rpm. Forty thermocouples are used in order to measure bearing element temperatures (babbitt, shaft, housing and oil baths). The influence of operating conditions and preload ratio on bearing performances are studied. Comparison between theoretical and experimental results is presented. The theoretical model is also performed on a large tilting-pad journal bearing which was investigated experimentally by other authors.

The Rolling-Pad Journal Bearing: A Promising Antiwhirl Configuration

1981 ◽  
Vol 23 (3) ◽  
pp. 131-141
Author(s):  
M. Malik ◽  
R. Sinhasan ◽  
D. V. Singh
Keyword(s):  
Journal Bearing ◽  
Dynamic Performance ◽  
Journal Bearings ◽  
Operating Conditions ◽  
Performance Characteristics ◽  
Tilting Pad ◽  
The Comparative Study ◽  
Tilting Pad Journal Bearing ◽  
Tilting Pad Journal Bearings ◽  
Theoretical Performance

The rolling-pad journal bearing is a kinematic variation of the well-known tilting-pad journal bearing. In rolling-pad bearings, the pads, instead of tilting about fixed pivots, roll at their back surfaces on the inside surface of a common sleeve to accommodate changes in the operating conditions of the bearing. This paper presents a comparison of the theoretical performance characteristics of rolling-pad journal bearings with those of tilting-pad journal bearings. The comparative study indicates that the dynamic performance characteristics of the rolling-pad bearing configuration are superior to those of the tilting-pad bearing.

Feasibility of Gas-Expanded Lubricants for Increased Energy Efficiency in Tilting-Pad Journal Bearings

2010 ◽  
Vol 132 (3) ◽  
Author(s):  
Andres Clarens ◽  
Amir Younan ◽  
Shibo Wang ◽  
Paul Allaire
Keyword(s):  
Supercritical Co2 ◽  
Power Loss ◽  
Load Capacity ◽  
Reducing Power ◽  
Journal Bearings ◽  
Operating Conditions ◽  
Eccentricity Ratio ◽  
Power Losses ◽  
Tilting Pad ◽  
Tilting Pad Journal Bearings

Lubricants are necessary in tilting-pad journal bearings to ensure separation between solid surfaces and to dissipate heat. They are also responsible for much of the undesirable power losses that can occur through a bearing. Here, a novel method to reduce power losses in tilting-pad journal bearings is proposed in which the conventional lubricant is substituted by a binary mixture of synthetic lubricant and dissolved CO2. These gas-expanded lubricants (GELs) would be delivered to a reinforced bearing housing capable of withstanding modest pressures less than 10 MPa. For bearings subject to loads that are both variable and predictable, GELs could be used to adjust lubricant properties in real time. High-pressure lubricants, mostly gases, have already been explored in tilting-pad journal bearings as a means to accommodate higher shaft speeds while reducing power losses and eliminating the potential for thermal degradation of the lubricant. These gas-lubricated bearings have intrinsic limitations in terms of bearing size and load capacity. The proposed system would combine the loading capabilities of conventional lubricated bearings with the efficiency of gas-lubricated bearings. The liquid or supercritical CO2 serves as a low-viscosity and completely miscible additive to the lubricant that can be easily removed by purging the gas after releasing the pressure. In this way, the lubricant can be fully recycled, as in conventional systems, while controlling the lubricant properties dynamically by adding liquid or supercritical CO2. Lubricant properties of interest, such as viscosity, can be easily tuned by controlling the pressure inside the bearing housing. Experimental measurements of viscosity for mixtures of polyalkylene glycol (PAG)+CO2 at various compositions demonstrate that significant reductions in mixture viscosity can be achieved with relatively small additions of CO2. The measured parameters are used in a thermoelastohydrodynamic model of tilting-pad journal bearing performance to evaluate the bearing response to GELs. Model estimates of power loss, eccentricity ratio, and pad temperature suggest that bearings would respond quite favorably over a range of speed and preload conditions. Calculated power loss reductions of 20% are observed when compared with both a reference petroleum lubricant and PAG without CO2. Pad temperature is also maintained without significant increases in eccentricity ratio. Both power loss and pad temperature are directly correlated with PAG-CO2 composition, suggesting that these mixtures could be used as “smart” lubricants responsive to system operating conditions.

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.

Sign in / Sign up

Export Citation Format

Share Document