scholarly journals Thermal Turbulent Flow in Leading Edge Grooved and Conventional Tilting Pad Journal Bearing Segments—A Comparative Study

Lubricants ◽  
2018 ◽  
Vol 6 (4) ◽  
pp. 97 ◽  
Author(s):  
Philip Croné ◽  
Andreas Almqvist ◽  
Roland Larsson
Keyword(s):  
Comparative Study ◽  
Journal Bearing ◽  
Flow Characteristics ◽  
Leading Edge ◽  
Inlet Temperature ◽  
Average Value ◽  
Tilting Pad ◽  
Sst Turbulence Model ◽  
Effective Boundary Condition ◽  
Tilting Pad Journal Bearing

A comparative study between a conventional- and leading edge grooved (LEG) tilting pad journal bearing (TPJB) segment is performed. The developed model uses the Shear Stress Transport (SST) turbulence model, coupled with the energy equation and a partial differential equation for the fluid domain mesh displacement to predict the thermal flow characteristics. Instead of using an effective boundary condition to determine the inlet temperature of the LEG pad and excluding the additional LEG portion, as is common practice, the whole geometry of the LEG is modeled. Several sizes of the LEG portion is investigated and it is shown to have quite a small influence on pressure, temperature, film thickness and turbulence intensity. Moreover, the results also show that the conventional pad gives rise to higher levels of turbulence in the mid plane compared to its LEG counterpart, while the latter has a marginally higher value of turbulence when the volume average value is computed. The maximum value of turbulence is however present in the conventional model.

scholarly journals Testing, Analysis, and CFD Modeling of a Profiled Leading Edge Groove Tilting Pad Journal Bearing

1998 ◽  
Author(s):  
Stephen L. Edney ◽  
Gregory B. Heitland ◽  
Scan M. DeCamillo
Keyword(s):  
High Speed ◽  
Journal Bearing ◽  
Leading Edge ◽  
Cfd Modeling ◽  
Operating Characteristics ◽  
Light Load ◽  
Operating Stability ◽  
Tilting Pad ◽  
Original Insight ◽  
Tilting Pad Journal Bearing

Testing and analysis of a profiled leading edge groove tilting pad journal bearing developed for light load operation is described. This bearing was designed for a generic, small, high speed steam turbine operating at projected loads of less than 25 psi (172.4 kPa) and journal surface speeds to 400 ft/s (122 m/s). On the second turbine application, a rotor instability was experienced with the oil flowrate reduced to optimize bearing steady state performance. This instability was eliminated by machining a taper on the exit side of the feed groove on each pad. At the reduced flowrate, the profiled groove bearing greatly improved the operating characteristics of the rotor system by reducing vibration amplitudes and stabilizing operation at speed. This paper is divided into two sections. The first section compares the rotordynamics analysis with test data that shows improved unbalance response and operating stability with the profiled groove bearing. The second section provides original insight of the effect of the profiled geometry on the bearing flow field using computational fluid dynamics models.

Optimization of a 900 mm Tilting-Pad Journal Bearing in Large Steam Turbines by Advanced Modeling and Validation

2018 ◽  
Author(s):  
Ümit Mermertas ◽  
Thomas Hagemann ◽  
Clément Brichart
Keyword(s):  
Steam Turbine ◽  
Power Plants ◽  
Journal Bearing ◽  
Leading Edge ◽  
Success Factor ◽  
Steam Turbines ◽  
Oil Supply ◽  
Modeling Methods ◽  
Tilting Pad ◽  
Tilting Pad Journal Bearing

Modernization of steam turbine components can extend the life of a power plant, decrease maintenance costs, increase service intervals and improve operational flexibility. However, this can also lead to challenging demands for existing components such as bearings, e.g., due to increased rotor weights. Therefore, a careful design and evaluation process of bearings is of major importance. This paper describes the advanced modeling methods applied for the optimization of a novel 900 mm three-pad tilting pad journal bearing followed by validation results that showed a high bearing temperature sensitivity to the fresh oil supply temperature during operation. The bearing was especially developed to cope with increased rotor weights within the framework of low pressure steam turbine modernizations at two similar 1000 MW nuclear power plants. With a static bearing load of approximately 2.7 MN at a rotor speed of 1500 rpm, it represents one of the highest loaded applications for tilting pad journal bearings in turbomachinery worldwide. After identification of the reasons for the sensitivity, advanced modeling methods were applied to optimize the bearing. For this purpose, a more comprehensive bearing model was developed taking into account the direct lubrication at the leading edge of the pads and the thermo-mechanical pad deformation. For the latter, a co-simulation between the bearing computation code and structural mechanics software was performed. The results of the entire analyses indicated modifications of bearing and pad clearance, pad pivot position, circumferential and axial pad length as well as pad thickness. Furthermore, the oil distribution into the pads was optimized by modifying the orifices within the bearing. The optimized bearing was then implemented on both units and proved its excellent operational behavior at increased fresh oil supply temperatures of up to 55°C. In addition, inspections during scheduled outages after 18 months of operation and subsequent restarts with reproducible bearing behavior confirmed the robustness of the optimized bearing. In conclusion, the application of advanced modeling methods proved to be the key success factor in the optimization of this bearing, which represents an optimal solution for large steam turbine and generator rotor train applications.

A Study of the Thermal Characteristics of the Leading Edge Groove and Conventional Tilting Pad Journal Bearings

1993 ◽  
Vol 115 (2) ◽  
pp. 219-226 ◽  
Author(s):  
W. Dmochowski ◽  
K. Brockwell ◽  
S. DeCamillo ◽  
A. Mikula
Keyword(s):  
Theoretical Analysis ◽  
Journal Bearing ◽  
Operating Temperature ◽  
Thermal Characteristics ◽  
Leading Edge ◽  
Journal Bearings ◽  
Tilting Pad ◽  
Tilting Pad Journal Bearing ◽  
Leg Design ◽  
Tilting Pad Journal Bearings

In this paper dealing with the tilting pad journal bearing, experimental results are presented which show that, at higher shaft speeds, the leading-edge-groove (LEG) design has significantly lower operating temperatures to those of the conventional design of tilting pad journal bearing. Subsequent theoretical analysis has shown that this reduction in pad operating temperature is the result of feeding cool oil directly to the leading edge of the pad. This has the effect of reducing the amount of hot oil carried over from one pad to the next.

Characteristics of a Spherical Seat TPJB With Four Methods of Directed Lubrication—Part II: Rotordynamic Performance

2017 ◽  
Vol 139 (12) ◽  
Author(s):  
David M. Coghlan ◽  
Dara W. Childs
Keyword(s):  
Matrix Model ◽  
Journal Bearing ◽  
Leading Edge ◽  
Dynamic Data ◽  
Rotordynamic Coefficients ◽  
Test Conditions ◽  
Tilting Pad ◽  
Frequency Independent ◽  
In Series ◽  
Tilting Pad Journal Bearing

Measured and predicted rotordynamic characteristics are presented for a four-pad, spherical-seat, tilting-pad journal bearing (TPJB) with 0.5 pivot offset, 0.6 L/D, 101.6 mm nominal diameter, and 0.3 preload in the load-between-pivots orientation. One bearing is tested four separate times in the following four different lubrication configurations: (1) flooded single-orifice (SO) at the bearing shell, (2) evacuated leading edge groove (LEG), (3) evacuated spray-bar blocker (SBB), and (4) evacuated spray-bar (SB). The same set of pads is used for every test to maintain clearance and preload; each method of lubrication is added as an assembly to the bearing. Test conditions include surface speeds and unit loads up to 85 m/s and 2.9 MPa, respectively. Dynamic data includes four sets (one set for each bearing configuration) of direct and cross-coupled rotordynamic coefficients derived from measurements and fit to a frequency-independent stiffness-damping-mass (KCM) matrix model. The pivot stiffness (pad and pivot in series) is measured and incorporated into predictions.

Characteristics of a Spherical-Seat TPJB With Four Methods of Directed Lubrication—Part I: Thermal and Static Performance

2017 ◽  
Vol 139 (12) ◽  
Author(s):  
David M. Coghlan ◽  
Dara W. Childs
Keyword(s):  
Journal Bearing ◽  
Thermal Characteristics ◽  
Leading Edge ◽  
Static Data ◽  
Axial Temperature ◽  
Tilting Pad ◽  
Thermal Data ◽  
In Series ◽  
Static Performance ◽  
Tilting Pad Journal Bearing

Static and thermal characteristics (measured and predicted) are presented for a four-pad, spherical-seat, tilting-pad journal bearing (TPJB) with 0.5 pivot offset, 0.6 L/D, 101.6 mm nominal diameter, and 0.3 preload in the load-between-pivots orientation. One bearing is tested four separate times in the following four different lubrication configurations: (1) flooded single-orifice (SO) at the bearing shell, (2) evacuated leading edge groove (LEG), (3) evacuated spray-bar blocker (SBB), and (4) evacuated spray-bar (SB). The LEG, SBB, and SB are all considered methods of “directed lubrication.” These methods rely on lubrication injected directly to the pad/rotor interface. The same set of pads is used for every test to maintain clearance and preload; each method of lubrication is added as an assembly to the bearing. Test conditions include surface speeds and unit loads up to 85 m/s and 2.9 MPa, respectively. Static data include rotor–bearing eccentricities and attitude angles. Thermal data include measured temperatures from 16 bearing thermocouples. Twelve of the bearing thermocouples are embedded in the babbitt layer of the pads, while the remaining four are oriented at the leading and trailing edge of the loaded pads exposed to the lubricant. Bearing thermocouples provide a circumferential and axial temperature gradient. The pivot stiffness (pad and pivot in series) is measured and incorporated into predictions.

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.

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.

Unsteady simulations of migration and deposition of fly-ash particles in the first-stage turbine of an aero-engine

2021 ◽  
pp. 1-21
Author(s):  
Z. Hao ◽  
X. Yang ◽  
Z. Feng
Keyword(s):  
Fly Ash ◽  
Film Cooling ◽  
Particle Deposition ◽  
Flow Characteristics ◽  
Leading Edge ◽  
Velocity Model ◽  
Operating Conditions ◽  
Inlet Temperature ◽  
Internal Cooling ◽  
Aero Engine

Abstract Particulate deposits in aero-engine turbines change the profile of blades, increase the blade surface roughness and block internal cooling channels and film cooling holes, which generally leads to the degradation of aerodynamic and cooling performance. To reveal particle deposition effects in the turbine, unsteady simulations were performed by investigating the migration patterns and deposition characteristics of the particle contaminant in a one-stage, high-pressure turbine of an aero-engine. Two typical operating conditions of the aero-engine, i.e. high-temperature take-off and economic cruise, were discussed, and the effects of particle size on the migration and deposition of fly-ash particles were demonstrated. A critical velocity model was applied to predict particle deposition. Comparisons between the stator and rotor were made by presenting the concentration and trajectory of the particles and the resulting deposition patterns on the aerofoil surfaces. Results show that the migration and deposition of the particles in the stator passage is dominated by the flow characteristics of fluid and the property of particles. In the subsequential rotor passage, in addition to these factors, particles are also affected by the stator–rotor interaction and the interference between rotors. With higher inlet temperature and larger diameter of the particle, the quantity of deposits increases and the deposition is distributed mainly on the Pressure Side (PS) and the Leading Edge (LE) of the aerofoil.

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