Thermo-hydrodynamic simulation study of twin-groove elliptical (two-lobe) journal bearing of steam turbine with experimental investigations

2020 ◽  
pp. 135065012097379
Author(s):  
Navin Kumar ◽  
Akash Shukla ◽  
Sanjay Bansal ◽  
Chandra B Khatri ◽  
Gannath D Thakre ◽  
...  
Keyword(s):  
Journal Bearing ◽  
Operating Conditions ◽  
Experimental Investigations ◽  
Inlet Temperature ◽  
Steam Turbines ◽  
Hydrodynamic Simulation ◽  
Load Carrying ◽  
Temperature Load ◽  
Fully Automatic ◽  
Hydrodynamic Journal Bearing

The present paper reports an experimental and theoretical investigation on performance behaviour of twin-groove elliptical (two-lobe) white metal hydrodynamic journal bearing used in steam turbines. The experiments are performed on a fully automatic journal bearing test rig with provisions to various operating conditions (i.e. load, speed, and lubricant temperature). The performance behaviour in terms of coefficient of friction, lubricant inlet temperature, load carrying capacity, journal displacement, weight loss etc. has been presented. In addition to this, numerical investigations have also been performed with the numerical solution of governing Reynolds equation using FEM (finite element method) technique and Jakobsson-Floberg-Olsson (JFO) boundary condition. The experimentally obtained and theoretical results have been correlated.

scholarly journals Effects of bushing profiles on the elastohydrodynamic lubrication performance of the journal bearing under steady operating conditions

2019 ◽  
Vol 20 (2) ◽  
pp. 207 ◽  
Author(s):  
Chongpei Liu ◽  
Bin Zhao ◽  
Wanyou Li ◽  
Xiqun Lu
Keyword(s):  
Journal Bearing ◽  
Elastohydrodynamic Lubrication ◽  
Operating Conditions ◽  
Asperity Contact ◽  
Parabolic Profile ◽  
Leakage Flow Rate ◽  
Lubrication Performance ◽  
Load Carrying ◽  
Edge Wear ◽  
Flow Rate Change

The bushing profiles have important effects on the performance of journal bearing. In this article, the effects of plain profile, double conical profile, and double parabolic profile on the elastohydrodynamic lubrication of the journal bearing under steady operating conditions are investigated. The journal misalignment and asperity contact between journal and bushing surface are considered, while the modification of the bushing profiles due to running-in is neglected. Finite element method is used for the elastic deformation of bushing surface, while the numerical solution is established by using finite difference method and overrelaxation iterative method. The numerical results reveal that the double parabolic profile with appropriate size can significantly increase the minimum film thickness and reduce the asperity contact pressure and friction, while the maximum film pressure, load-carrying capacity, and leakage flow rate change slightly under steady operating conditions. This study may help to reduce the edge wear and prolong the service life of the journal bearing.

Effects of double parabolic profiles with groove textures on the hydrodynamic lubrication performance of journal bearing under steady operating conditions

2020 ◽  
Vol 21 (3) ◽  
pp. 301
Author(s):  
Chongpei Liu ◽  
Wanyou Li ◽  
Xiqun Lu ◽  
Bin Zhao
Keyword(s):  
Journal Bearing ◽  
Hydrodynamic Lubrication ◽  
Operating Conditions ◽  
Lubricating Oil ◽  
Asperity Contact ◽  
Adiabatic Flow ◽  
Lubrication Performance ◽  
Load Carrying ◽  
Edge Wear ◽  
Journal Misalignment

The textures on the bushing surface have important effects on the performance of journal bearing. In this study, the effects of double parabolic profiles with groove textures on the hydrodynamic lubrication performance of journal bearing under steady operating conditions are investigated theoretically. The journal misalignment, asperity contact and thermal effects are considered, while the profile modifications due to running-in are neglected. The Winkler/Column model is used to calculate the elastic deformation of bushing surface and the adiabatic flow hypothesis is adopted to obtain the effective temperature of lubricating oil. The numerical solution is established by using finite difference and overrelaxation iterative methods, and the rupture zone of oil film is determined by Reynolds boundary conditions. The numerical results reveal that the double parabolic profiles with groove textures with proper location and geometric sizes can increase load carrying capacity and reduce friction loss under steady operating conditions, which effectively overcome the drawbacks of double parabolic profiles. This novel bushing profile may help to reduce the bushing edge wear and enhance the lubrication performance of journal bearing.

scholarly journals Rotordynamics analysis of solar hybrid microturbine for concentrated solar power

2020 ◽  
Vol 11 (1) ◽  
pp. 38
Author(s):  
Maulana Arifin
Keyword(s):  
High Speed ◽  
Journal Bearing ◽  
Operating Conditions ◽  
Inlet Temperature ◽  
Direct Normal Irradiance ◽  
Linear Vibrations ◽  
Parabolic Dish ◽  
Design Speed ◽  
Rotor Assembly ◽  
Tip Displacement

Microturbine based on a parabolic dish solar concentrator runs at high speed and has large amplitudes of subsynchronous turbo-shaft motion due to the direct normal irradiance (DNI) fluctuation in daily operation. A detailed rotordynamics model coupled to a full fluid film radial or journal bearing model needs to be addressed for increasing performance and to ensure safe operating conditions. The present paper delivers predictions of rotor tip displacement in the microturbine rotor assembly supported by a journal bearing under non-linear vibrations. The rotor assembly operates at 72 krpm on the design speed and delivers a 40 kW power output with the turbine inlet temperature is about 950 °C. The turbo-shaft oil temperature range is between 50 °C to 90 °C. The vibrations on the tip radial compressor and turbine were presented and evaluated in the commercial software GT-Suite environment. The microturbine rotors assembly model shows good results in predicting maximum tip displacement at the rotors with respect to the frequency and time domain.

A Study on Energetic and Hydraulic Interaction of Combined Journal and Thrust Bearings

2015 ◽  
Author(s):  
Thomas Hagemann ◽  
Hardwig Blumenthal ◽  
Christian Kraft ◽  
Hubert Schwarze
Keyword(s):  
Boundary Conditions ◽  
High Speed ◽  
Thrust Bearing ◽  
Journal Bearing ◽  
Measurement Data ◽  
Operating Conditions ◽  
Experimental Investigations ◽  
Minor Importance ◽  
Thrust Bearings ◽  
Side Flow

A theoretical algorithm for the analysis of bidirectional interaction of combined journal and thrust bearings is presented. While many theoretical and experimental investigations on the operating behavior of single journal and thrust bearings can be found only few results for combined bearings are available. However, combined bearings interact by exchanging lubricant and heat which can affect significant changes of boundary conditions compared to a single bearing application. Therefore, a novel procedure is developed to combine two separate codes for journal and thrust bearings in order to iteratively determine the coupling boundary conditions due to the special design of the entire bearing unit. The degree of interaction strongly depends on the type of lubrication. In a first step predictions are verified by measurement data for a combined bearing with a fixed-pad offset-halves journal bearing and a directed lubricated tilting-pad thrust bearing. Experiments were conducted on a high speed test rig up to sliding speeds of 107 m/s at the mean radius of the thrust bearing. As expected the interaction of the two oil films is comparably low in the investigated speed and load range for this bearing design because of the active lubrication of both bearings and the low hydraulic resistance of the thrust bearing. In order to theoretically investigate interaction of thrust and journal bearings in more details a combined bearing with fixed-pad thrust parts lubricated exclusively by the side flow of the journal bearing is studied. A variation of modeling level, pocket design of the journal part, thrust load and rotating frequency provides the following results: (i) hydraulic and energetic interaction have to be modelled in details, (ii) the axial flow resistance of the pockets strongly influences flow rates and the pressure level at the interfaces (iii) the level of interface pressure rises with increasing thrust loads and decreasing rotor speed, (iv) the axial bearing clearance is rather of minor importance for the investigated bearing. Finally, improvements in order to predict operating conditions more precisely are comprehensively discussed.

Design and Development of Permanent Magneto-Hydrodynamic Hybrid Journal Bearing

2017 ◽  
Vol 139 (4) ◽  
Author(s):  
K. P. Lijesh ◽  
Harish Hirani
Keyword(s):  
Journal Bearing ◽  
Hydrodynamic Lubrication ◽  
Magnetic Bearing ◽  
Operating Conditions ◽  
Fluid Film ◽  
Test Setup ◽  
Fluid Film Bearings ◽  
Lubrication Regime ◽  
Load Carrying ◽  
Hybrid Bearing

Fluid film bearings (FFBs) provide economic wear-free performance when operating in hydrodynamic lubrication regime. In all other operating conditions, except hydrostatic regime, these bearings are subjected to wear. To get wear-free performance even in those conditions, a hybrid (hydrodynamic + rotation magnetized direction (RMD) configured magnetic) bearing has been proposed. The hybrid bearing consists of square magnets to repel the shaft away from the bearing bore. Load-carrying capacities of four configurations of hybrid bearings were determined. The results are presented in this paper. The best configuration of hybrid bearing was developed. A test setup was developed to perform the experiments on the fluid film and hybrid bearings. The wear results of both the bearings under same operating conditions are presented.

Numerical Analysis of Static Characteristics of Herringbone Grooved Hydrodynamic Journal Bearing

2011 ◽  
Vol 105-107 ◽  
pp. 2259-2262
Author(s):  
Han Ting Zhu ◽  
Qian Ding
Keyword(s):  
Journal Bearing ◽  
Normal Pressure ◽  
Differential Method ◽  
Static Characteristics ◽  
Load Carrying ◽  
Significant Performance ◽  
Hydrodynamic Journal Bearing ◽  
The Stability ◽  
Spiral Angle ◽  
Selection Of

By means of the finite differential method, the Reynolds equation is solved and the static characteristics of herringbone grooved hydrodynamic journal bearing are numerically analyzed by presenting the circumferential and axial pressures. The influences of parameters such as the eccentricity, width-diameter ratio of bearing, spiral angle, depth and number of grooves, on the static characteristics of herringbone grooved bearing are discussed. The results indicate that the normal pressure of oil film and the load carrying capacity as well, of herringbone grooved bearing will decrease with the increase of groove number and depth. On the other hand, as the pressure distributes in wider area in the circumferential direction, the stability of bearing can be improved. In consideration of these two aspects, the optimal groove number is 8-12, and the selection of depth and screw angle of grooves should also be chosen carefully to obtain the significant performance of herringbone grooved bearing.

scholarly journals THERMOHYDRODYNAMIC PERFORMANCE OF A JOURNAL BEARING WITH 3D-SURFACE ROUGHNESS AND FLUID INERTIA EFFECTS

2012 ◽  
pp. 243-249
Author(s):  
E. SUJITH PRASAD ◽  
T. NAGARAJU ◽  
J. PREM SAGAR
Keyword(s):  
Surface Roughness ◽  
Journal Bearing ◽  
Roughness Parameter ◽  
Theoretical Work ◽  
Fluid Film ◽  
Fluid Inertia ◽  
Inertia Effects ◽  
3D Surface Roughness ◽  
Load Carrying ◽  
Hydrodynamic Journal Bearing

This theoretical work describe the combined influence of surface roughness, thermal and fluid-inertia effects on performance characteristics of hydrodynamic journal bearing. The average Reynolds equation that modified to include the surface roughness, viscosity variation due to temperature rise in lubricant fluid-film and fluid-inertia is used to obtain pressure field in the fluid-film. The matched solutions of modified average Reynolds, energy and conduction equations are obtained using finite element method and appropriate iterative schemes. The effects of surface roughness parameter, roughness orientation, and roughness characteristics of opposing surfaces on circumferential fluid-film pressure distribution, load carrying capacity and stability threshold speed of the bearing are studied by considering thermal and fluid-inertia effects.

scholarly journals Evaluation of Load Carrying Capacity of Hydrodynamic Journal Bearing with Nanolubricants

10.29007/pq98 ◽  
2018 ◽  
Author(s):  
Tushar Gundarneeya ◽  
Dipak Vakharia
Keyword(s):  
Carrying Capacity ◽  
Journal Bearing ◽  
Volume Fraction ◽  
Classical Model ◽  
Viscosity Model ◽  
Load Carrying Capacity ◽  
Base Oil ◽  
Lubricant Oil ◽  
Load Carrying ◽  
Hydrodynamic Journal Bearing

In this work, influence of nanolubricants on the load carrying capacity of hydrodynamic journal bearing is studied. Increase in viscosity of lubricant oil with nanopartical as lubricant additives is modeled using different classical model and compared with Kriger-Doughetry viscosity model. This Kriger-Doughetry viscosity model for simulating viscosity of nanolubricant is validated by Experimental verification using reheometer. The pressure distribution and load carrying capacity are theoretically analyzed using Reynolds Equation for Reynolds boundary condition for different concentration of nanoparticles volume fraction. Result reveal increase in pressure and load carrying capacity of Journal bearing with nanolubricants in comparison to base oil.

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.

Load-Carrying Capacity Analysis for Sinusoidal Surfaces Hydrodynamic Bearing

2011 ◽  
Vol 295-297 ◽  
pp. 1244-1250
Author(s):  
Jian Xi Yang ◽  
Fa Yu Zhang ◽  
Jian Ting Liu ◽  
Jian Fang Zhou
Keyword(s):  
Carrying Capacity ◽  
Journal Bearing ◽  
Mathematic Model ◽  
Journal Bearings ◽  
Capacity Analysis ◽  
Load Carrying Capacity ◽  
Hydrodynamic Bearing ◽  
Load Carrying ◽  
Hydrodynamic Journal Bearing ◽  
Sinusoidal Surface

To obtain a new method to improve hydrodynamic bearing carrying capacity, hydrodynamic journal bearing’s characteristics as well as the current study direction are analyzed. According to the calculation of general cylindrical hydrodynamic journal bearing, the mathematic model for sinusoidal surface hydrodynamic bearing’s carrying capacity is established. It is used to calculate, analyze and compare these two bearings’ carrying capacity with example. The bearing, which has the characteristic of sinusoidal surface, has stronger carrying capacity than general cylindrical hydrodynamic bearing. What’s more, the improvement is more obvious when the number of waves is 3, also it has wider carrying area. Compared with other journal bearings, the journal bearing with sinusoidal surfaces has stronger carrying capacity, smaller friction moment and longer life-span. Therefore, it has extensive prospect.

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