scholarly journals Prediction on Flow and Thermal Characteristics of Ultrathin Lubricant Film of Hydrodynamic Journal Bearing

Micromachines ◽  
2021 ◽  
Vol 12 (10) ◽  
pp. 1208
Author(s):  
Yulong Jiang ◽  
Bo Liang ◽  
Zhongwen Huang ◽  
Zhenqian Chen ◽  
Bo Xu
Keyword(s):  
Flow Rate ◽  
Heat Dissipation ◽  
Journal Bearing ◽  
Thermal Characteristics ◽  
Lubricant Film ◽  
Rotating Speed ◽  
Slip Boundary ◽  
Theoretical Support ◽  
Hydrodynamic Journal Bearing ◽  
Temperature Liquid

This paper focuses on the flow and thermal characteristics of the lubricant film in the micro clearance of a hydrodynamic journal bearing (HJB) at high rotating speed. A thermohydrodynamic (THD) method consists of the Reynolds equation coupled with energy and viscosity-temperature equation with considering the cavitation is put forward. The 3D surface diagrams of the lubricant film thickness, pressure, temperature, liquid mass fraction, flow rate and heat dissipation distributions under different geometric, operating, slip and no-slip boundary conditions are systemically exhibited and analyzed. The results show that with the rise of eccentricity or length diameter ratio, the maximum peaks of pressure, temperature and heat dissipation are rapidly increased, the cavitation is aggravated, and the flow rate is accelerated in different extent. As the bearing speed accelerating, the maximum peak of temperature is strongly increased, whereas, the distinction between peaks of flow rate and heat dissipation is magnified and reduced, respectively. It provides a fruitful inside view of the inner flow and thermal characterizations of HJB for further understanding its flow-thermal interaction mechanisms and offers theoretical support for improving its working performance.

Effect of Slip Boundary Condition and Non-Newtonian Rheology of Lubricants on the Dynamic Characteristics of Finite Hydrodynamic Journal Bearing

2021 ◽  
Author(s):  
Mohammad Arif ◽  
Saurabh Kango ◽  
Dinesh Kumar Shukla
Keyword(s):  
Boundary Condition ◽  
Dynamic Stability ◽  
Journal Bearing ◽  
Mass Parameter ◽  
Critical Mass ◽  
Slip Boundary Condition ◽  
Slip Effect ◽  
Slip Boundary ◽  
Slip Region ◽  
Hydrodynamic Journal Bearing

Abstract In the present study, the influence of various slip zone locations on the dynamic stability of finite hydrodynamic journal bearing lubricated with non-Newtonian and Newtonian lubricants has been investigated. Linearized equation of motion with free vibration of rigid rotor has been used to find the optimum location of the slip region with maximum stability margin limit. It has been observed that bearing with interface of slip and no-slip region near the upstream side of minimum film-thickness location is effective in improving the direct and cross stiffness coefficient, critical mass parameter, and critical whirling speed. The magnitude of dynamic performance parameters with slip effect is highly dependent on the rheology of lubricant. Shear-thinning lubricants combined with slip boundary condition shows higher dynamic stability as compared to the Newtonian lubricants under the conventional boundary condition. For all considered rheology of lubricants, the dynamic stability of bearing with slip effect is improving by increasing the eccentricity ratio.

scholarly journals Multiphase Computational Fluid Dynamics Analysis of Hydrodynamic Journal Bearing Under the Combined Influence of Texture and Slip

Lubricants ◽  
2019 ◽  
Vol 7 (11) ◽  
pp. 97 ◽  
Author(s):  
Mohammad Tauviqirrahman ◽  
J. Jamari ◽  
Bayu Siswo Wibowo ◽  
Hilmy Muhammad Fauzan ◽  
M. Muchammad
Keyword(s):  
Environmental Sustainability ◽  
Journal Bearing ◽  
Fluid Dynamic ◽  
Surface Texturing ◽  
System Component ◽  
Textured Surface ◽  
Computational Fluid Dynamic Analysis ◽  
Slip Boundary ◽  
Computational Fluid Dynamics Analysis ◽  
Hydrodynamic Journal Bearing

The drive to maintain the environmental sustainability and save the global energy consumption is urgent, making every powertrain system component a candidate to enhance efficiency. In this work, the combined effects of the slip boundary and textured surface in hydrodynamic journal bearing as one of the critical components in industrial powertrain and engine systems are assessed using a multiphase computational fluid dynamic analysis that allows for phase change in a cavitation process and arbitrary textured geometry. The texture studied consists of regularly spaced rectangular dimples through two-dimensional (infinitely long) journal bearing. The modified Navier–slip model is employed to describe the slip boundary condition. A systematic comparison is made for various textured configurations varying the texture depth and the length of the texturing zone with respect to the performance of a smooth (untextured) bearing for several eccentricity ratios. The effectiveness of the texture with or without slip at enhancing the load support over a corresponding smooth bearing is investigated with the parameters. The detrimental or beneficial effect of surface texturing as well as the slip promotion is explained in terms of the mechanisms of pressure generation for several eccentricity ratios. The results of the present work indicate that journal bearing textured by a proper texturing zone and dimple depth are characterized by substantial load support levels. However, in the range of high eccentricity ratios, the promotion of texturing and slip can significantly degrade the performance of the load support.

Influence of Thermal Conductivity of Lubricant on the THD Characteristics of a Plain Journal Bearing

1991 ◽  
Author(s):  
C. Rajalingham ◽  
B. S. Prabhu ◽  
R. B. Bhat ◽  
G. D. Xistris
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Temperature Variation ◽  
Heat Generation ◽  
Journal Bearing ◽  
Lubricant Film ◽  
Fluid Film ◽  
Adiabatic Conditions ◽  
Viscous Heat ◽  
Hydrodynamic Journal Bearing

Abstract The viscous heat generation in the lubricant film of a hydrodynamic journal bearing causes a rise in temperature of the fluid film. Considering the influence of the temperature variation along and across the film, the performance of a journal bearing is investigated under adiabatic conditions for different values of thermal conductivity of the lubricant. In this analysis, the temperature of the journal surface has been chosen to ensure that there is no net heat transfer from the lubricant The results show that the variation of temperature across the film affects bearing performance significantly and that an increase in lubricant thermal conductivity enhances bearing performance.

Hydrostatic Journal Bearing With Porous Pads and Improved Properties

2019 ◽  
Vol 141 (12) ◽  
Author(s):  
Dein Shaw ◽  
Hui-An Hsieh
Keyword(s):  
Theoretical Model ◽  
Flow Rate ◽  
Cylindrical Surface ◽  
Journal Bearing ◽  
Load Capacity ◽  
Simulation Software ◽  
Rotating Speed ◽  
Hydrostatic Bearing ◽  
Flow Through ◽  
Hydrodynamic Effects

Abstract A hydrostatic journal bearing with porous pads to improve its performance is designed. The porous pads, which are embedded in recesses of the hydrostatic journal bearing, not only allow lubricant to flow through them but also form a complete cylindrical surface with the bearing land. The load capacity of the hydrostatic bearing is thus maintained and the hydrodynamic effects strengthened. A theoretical model of the porous pads bearing is tested with the simulation software, and the parameters that critically affect the bearing performance are studied. Thus, the results obtained indicate that the porous pads bearing has higher load capacity and higher stiffness than a typical hydrostatic bearing with lower friction and lower end flow rate at high rotating speed.

Paper 15: Thermal Aspects of Hydrodynamic Journal Bearing Performance at High Speeds

1966 ◽  
Vol 181 (15) ◽  
pp. 127-135 ◽  
Author(s):  
R. G. Woolacott ◽  
W. L. Cooke
Keyword(s):  
Flow Rate ◽  
Journal Bearing ◽  
Journal Bearings ◽  
Inlet Temperature ◽  
Flow Rates ◽  
High Speeds ◽  
Lubricant Flow ◽  
Hydrodynamic Journal Bearing ◽  
Temperature And Pressure

This paper describes a rig for testing journal bearings at high speeds under steady loads and reports on measurements of bearing and lubricant temperatures and lubricant flow-rates for hydrodynamic journal bearings operating at speeds up to 35 000 rev/min and mean bearing pressures up to 3333 lbf/in2. Variations of temperature and flow-rate with load, speed, oil-inlet temperature and pressure, clearance, and oil-inlet grooving are also described, and the effects of bearing and lubricant temperatures on bearing performance are discussed.

An Analytic Model of Oil-Film Force on Hydrodynamic Journal Bearing of Finite Length

2008 ◽  
Author(s):  
JinFu Yang ◽  
Ce Chen ◽  
ShengBo Yang ◽  
DaRen Yu ◽  
Ying Cui ◽  
...  
Keyword(s):  
Finite Length ◽  
Journal Bearing ◽  
Slip Boundary Condition ◽  
Analytic Model ◽  
Clearance Ratio ◽  
Oil Film ◽  
Slip Boundary ◽  
Proposed Model ◽  
Speed Up ◽  
Hydrodynamic Journal Bearing

In order to more clearly express the interrelation between the oil-film force on hydrodynamic journal bearing of finite length and the wedging, whiling, and squeezing motions of journals, an analytic model with well-defined physical meaning is proposed in this paper by introducing the non-slip boundary condition for the oil-film velocity gradient without modifying the basic assumption for Reynolds equation to formulate the expression of oil-film pressure distribution, obtaining the analytic solution of oil-film force through integration of circumferential pressure, and defining the effect coefficients for wedging, whirling and squeezing motions, which are related to the clearance ratio and eccentricity ratio of bearings. The proposed model is compared with an existing model to show off its advantage. The proposed model was also applied to a 200MW steam turbine low-pressure rotor-bearing system to simulate the dynamic response of the rotor during the speed-up process. The analytic results of this application proved the validity of the proposed model.

scholarly journals Design and thermal characteristic analysis of motorized spindle cooling system

2021 ◽  
Vol 13 (5) ◽  
pp. 168781402110208
Author(s):  
Yuan Zhang ◽  
Lifeng Wang ◽  
Yaodong Zhang ◽  
Yongde Zhang
Keyword(s):  
Flow Rate ◽  
High Speed ◽  
Thermal Deformation ◽  
Cooling System ◽  
Thermal Characteristic ◽  
Water Flow Rate ◽  
Thermal Characteristics ◽  
Characteristic Analysis ◽  
Motorized Spindle ◽  
Experiment And Simulation

The thermal deformation of high-speed motorized spindle will affect its reliability, so fully considering its thermal characteristics is the premise of optimal design. In order to study the thermal characteristics of high-speed motorized spindles, a coupled model of thermal-flow-structure was established. Through experiment and simulation, the thermal characteristics of spiral cooling motorized spindle are studied, and the U-shaped cooled motorized spindle is designed and optimized. The simulation results show that when the diameter of the cooling channel is 7 mm, the temperature of the spiral cooling system is lower than that of the U-shaped cooling system, but the radial thermal deformation is greater than that of the U-shaped cooling system. As the increase of the channel diameter of U-shaped cooling system, the temperature and radial thermal deformation decrease. When the diameter is 10 mm, the temperature and radial thermal deformation are lower than the spiral cooling system. And as the flow rate increases, the temperature and radial thermal deformation gradually decrease, which provides a basis for a reasonable choice of water flow rate. The maximum error between experiment and simulation is 2°C, and the error is small, which verifies the accuracy and lays the foundation for future research.

Experimental Investigation on Cavitation Characteristics of a Three-Groove Journal Bearing

2013 ◽  
Vol 420 ◽  
pp. 47-50
Author(s):  
Ying Yang ◽  
Jing Hua Dai
Keyword(s):  
Experimental Investigation ◽  
High Speed ◽  
Journal Bearing ◽  
Rupture Zone ◽  
Work Characteristics ◽  
Oil Film ◽  
Rotating Speed ◽  
Clear Effect ◽  
Supply Pressure

Under high and super-high speed, oil film of the journal bearing is easy to crack and then becomes cavitation. The existence of cavitation has an important effect on the work characteristics of the shaft. On the journal bearing experiment rig the cavitation characteristics of the three-groove journal beaing were studied. The influences of the shaft rotating speed and supply pressure on cavitation shape were investigated. The results show that rotating speed and supply pressure have a clear effect on the cavitation shape, and the number of cavitation strip in the rupture zone decreases when the supply pressure increases.

Heat and Mass Transfer to Air in a Cross Flow Heat Exchanger with Surface Deluge Cooling

2016 ◽  
Vol 24 (01) ◽  
pp. 1650002 ◽  
Author(s):  
Andrea Diani ◽  
Luisa Rossetto ◽  
Roberto Dall’Olio ◽  
Daniele De Zen ◽  
Filippo Masetto
Keyword(s):  
Heat Exchanger ◽  
Heat Flow ◽  
Flow Rate ◽  
Data Center ◽  
Heat Dissipation ◽  
Cross Flow ◽  
Critical Conditions ◽  
Heat Flow Rate ◽  
External Temperature ◽  
Flow Heat

Cross flow heat exchangers, when applied to cool data center rooms, use external air (process air) to cool the air stream coming from the data center room (primary air). However, an air–air heat exchanger is not enough to cope with extreme high heat loads in critical conditions (high external temperature). Therefore, water can be sprayed in the process air to increase the heat dissipation capability (wet mode). Water evaporates, and the heat flow rate is transferred to the process air as sensible and latent heat. This paper proposes an analytical approach to predict the behavior of a cross flow heat exchanger in wet mode. The theoretical results are then compared to experimental tests carried out on a real machine in wet mode conditions. Comparisons are given in terms of calculated versus experimental heat flow rate and evaporated water mass flow rate, showing a good match between theoretical and experimental values.

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