The Comparative Performance of Energy Efficient, Tilting Pad Thrust Bearings for High Speed Applications

1992 ◽  
Vol 35 (2) ◽  
pp. 245-252 ◽  
Author(s):  
J. E. L. Simmons ◽  
S. D. Advani
Keyword(s):  
Energy Efficient ◽  
High Speed ◽  
Comparative Performance ◽  
Thrust Bearings ◽  
Tilting Pad

Effect of Hydrodynamic Thrust Bearings on Lateral Shaft Vibrations

1991 ◽  
Vol 113 (4) ◽  
pp. 811-817 ◽  
Author(s):  
N. Mittwollen ◽  
T. Hegel ◽  
J. Glienicke
Keyword(s):  
High Speed ◽  
High Surface ◽  
Considerable Effect ◽  
Computational Method ◽  
Sliding Bearings ◽  
Thrust Bearings ◽  
Lateral Vibrations ◽  
Tilting Pad ◽  
Convenient Model

A computational method for the prediction of static and dynamic characteristic data of tilting pad and fixed pad thrust bearings for high surface velocities and high thermal loads is developed and verified. Furthermore, a convenient model is presented, which allows the determination of the dynamic coefficients for the gyrating movement of the thrust collar, where it is sufficient using the purely axial dynamic single pad coefficients only. Introducing these coefficients into an accordingly modified rotor dynamics program, the lateral vibrations of a high speed rotor with sliding bearings are calculated and a considerable effect of the thrust bearings is shown. These theoretical results are also verified experimentally through vibration measurements at a high speed rotor test rig.

Effects of High-Operating Speeds on Tilting Pad Thrust Bearing Performance

1976 ◽  
Vol 98 (1) ◽  
pp. 73-79 ◽  
Author(s):  
J. W. Capitao ◽  
R. S. Gregory ◽  
R. P. Whitford
Keyword(s):  
Experimental Data ◽  
Flow Rate ◽  
Power Loss ◽  
High Speed ◽  
Thrust Bearing ◽  
Full Scale ◽  
Thrust Bearings ◽  
Tilting Pad ◽  
Speed Performance ◽  
Bearing Loads

A comparison of the high-speed performance characteristics of tilting-pad, self-equalizing type thrust bearings through two independent full-scale programs is reported. This paper presents experimental data on centrally pivoted, 6-pad, 267-mm (10 1/2-in.) and 304-mm (12-in.) O.D. bearings operating at shaft speeds up to 14000 rpm and bearing loads ranging up to 2.76 MPa (400 psi). Data presented demonstrate the effects of speed and loading on bearing power loss and metal temperatures. Included is a discussion of optimum oil supply flow rate based upon considerations of bearing pad temperatures and power loss values.

Paper 13: Tilting Pad Thrust Bearings: Factors Affecting Performance and Improvements with Directed Lubrication

1969 ◽  
Vol 184 (12) ◽  
pp. 93-102 ◽  
Author(s):  
M. K. Bielec ◽  
A. J. Leopard
Keyword(s):  
Film Thickness ◽  
High Speed ◽  
Thrust Bearing ◽  
Specific Pressure ◽  
Factors Affecting ◽  
Oil Film ◽  
Thrust Bearings ◽  
Tilting Pad ◽  
External Variables ◽  
Factors Affecting Performance

The effect on flooded tilting pad thrust bearing performance of a number of external variables is examined. At sliding speeds between 10 and 100 m/s, and for specific pressure between 15 bar and 55 bar, measurements were made of oil film thickness, bearing temperature, and power loss for various oil inlet systems, oil quantities, housing pressures, and degrees of misalignment. Power consumption in high-speed thrust bearings can be safely reduced by the use of directed lubrication with a drained casing, bearing temperature being reduced and oil film thickness increased.

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.

Influence of new surface micro-structures on the performance behaviours of fluid film tilting pad thrust bearings

2021 ◽  
pp. 095440622110309
Author(s):  
JC Atwal ◽  
RK Pandey
Keyword(s):  
Mass Conservation ◽  
Performance Parameters ◽  
Algebraic Equations ◽  
The Finite Element Method ◽  
Thrust Bearings ◽  
Lubrication Equation ◽  
Tilting Pad ◽  
Minimum Film Thickness ◽  
Newton Raphson ◽  
Micro Structures

Performance parameters such as power loss, minimum film thickness, and maximum oil temperature of the sector-shaped tilting pad thrust bearings employing the new micro-structural geometries on pad surfaces have been investigated. The lubrication equation incorporating the mass-conservation issue is discretized using the finite element method and the solution of resulting algebraic equations is obtained employing a Newton-Schur method. The pad equilibrium in the analysis is established using the Newton-Raphson and Braydon methods. The influence of attributes of micro-structures such as depth, circumferential and radial positioning extents have been explored on the performance behaviours. It is found that with the new micro-structured pad surfaces, the performance parameters significantly improved in comparison to conventional plain and conventional rectangular pocketed pads.

scholarly journals Dual-shot dynamics and ultimate frequency of all-optical magnetic recording on GdFeCo

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Sicong Wang ◽  
Chen Wei ◽  
Yuanhua Feng ◽  
Hongkun Cao ◽  
Wenzhe Li ◽  
...  
Keyword(s):  
Magnetization Reversal ◽  
Energy Efficient ◽  
High Speed ◽  
Data Transfer ◽  
Laser Pulses ◽  
Time Resolved ◽  
All Optical ◽  
Fs Laser ◽  
High Speed Data ◽  
Natural Way

AbstractAlthough photonics presents the fastest and most energy-efficient method of data transfer, magnetism still offers the cheapest and most natural way to store data. The ultrafast and energy-efficient optical control of magnetism is presently a missing technological link that prevents us from reaching the next evolution in information processing. The discovery of all-optical magnetization reversal in GdFeCo with the help of 100 fs laser pulses has further aroused intense interest in this compelling problem. Although the applicability of this approach to high-speed data processing depends vitally on the maximum repetition rate of the switching, the latter remains virtually unknown. Here we experimentally unveil the ultimate frequency of repetitive all-optical magnetization reversal through time-resolved studies of the dual-shot magnetization dynamics in Gd27Fe63.87Co9.13. Varying the intensities of the shots and the shot-to-shot separation, we reveal the conditions for ultrafast writing and the fastest possible restoration of magnetic bits. It is shown that although magnetic writing launched by the first shot is completed after 100 ps, a reliable rewriting of the bit by the second shot requires separating the shots by at least 300 ps. Using two shots partially overlapping in space and minimally separated by 300 ps, we demonstrate an approach for GHz magnetic writing that can be scaled down to sizes below the diffraction limit.

scholarly journals NanoLEDs for energy-efficient and gigahertz-speed spike-based sub-λ neuromorphic nanophotonic computing

Nanophotonics ◽  
2020 ◽  
Vol 9 (13) ◽  
pp. 4149-4162 ◽  
Author(s):  
Bruno Romeira ◽  
José M. L. Figueiredo ◽  
Julien Javaloyes
Keyword(s):  
Neural Networks ◽  
Energy Efficient ◽  
High Speed ◽  
Dynamic Properties ◽  
Optical Computing ◽  
Differential Conductance ◽  
Rate Equations ◽  
Dynamical Equations ◽  
Electrical Modulation ◽  
High Bandwidth

AbstractEvent-activated biological-inspired subwavelength (sub-λ) photonic neural networks are of key importance for future energy-efficient and high-bandwidth artificial intelligence systems. However, a miniaturized light-emitting nanosource for spike-based operation of interest for neuromorphic optical computing is still lacking. In this work, we propose and theoretically analyze a novel nanoscale nanophotonic neuron circuit. It is formed by a quantum resonant tunneling (QRT) nanostructure monolithic integrated into a sub-λ metal-cavity nanolight-emitting diode (nanoLED). The resulting optical nanosource displays a negative differential conductance which controls the all-or-nothing optical spiking response of the nanoLED. Here we demonstrate efficient activation of the spiking response via high-speed nonlinear electrical modulation of the nanoLED. A model that combines the dynamical equations of the circuit which considers the nonlinear voltage-controlled current characteristic, and rate equations that takes into account the Purcell enhancement of the spontaneous emission, is used to provide a theoretical framework to investigate the optical spiking dynamic properties of the neuromorphic nanoLED. We show inhibitory- and excitatory-like optical spikes at multi-gigahertz speeds can be achieved upon receiving exceptionally low (sub-10 mV) synaptic-like electrical activation signals, lower than biological voltages of 100 mV, and with remarkably low energy consumption, in the range of 10–100 fJ per emitted spike. Importantly, the energy per spike is roughly constant and almost independent of the incoming modulating frequency signal, which is markedly different from conventional current modulation schemes. This method of spike generation in neuromorphic nanoLED devices paves the way for sub-λ incoherent neural elements for fast and efficient asynchronous neural computation in photonic spiking neural networks.

scholarly journals Fog Computing-Assisted Energy-Efficient Resource Allocation for High-Mobility MIMO-OFDMA Networks

2018 ◽  
Vol 2018 ◽  
pp. 1-8
Author(s):  
Lingyun Lu ◽  
Tian Wang ◽  
Wei Ni ◽  
Kai Li ◽  
Bo Gao
Keyword(s):  
Resource Allocation ◽  
Energy Efficient ◽  
High Speed ◽  
Optimization Problem ◽  
Fog Computing ◽  
High Mobility ◽  
High Speed Train ◽  
Efficient Resource ◽  
Energy Efficient Resource Allocation ◽  
System Configurations

This paper presents a suboptimal approach for resource allocation of massive MIMO-OFDMA systems for high-speed train (HST) applications. An optimization problem is formulated to alleviate the severe Doppler effect and maximize the energy efficiency (EE) of the system. We propose to decouple the problem between the allocations of antennas, subcarriers, and transmit powers and solve the problem by carrying out the allocations separately and iteratively in an alternating manner. Fast convergence can be achieved for the proposed approach within only several iterations. Simulation results show that the proposed algorithm is superior to existing techniques in terms of system EE and throughput in different system configurations of HST applications.

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