On the Thrust Bearing Characteristics in Turbulent Flow

1981 ◽  
Vol 103 (3) ◽  
pp. 453-458 ◽  
Author(s):  
K. Venkateswarlu ◽  
Cz. M. Rodkiewicz
Keyword(s):  
Theoretical Analysis ◽  
Turbulent Flow ◽  
Numerical Method ◽  
Eddy Viscosity ◽  
Thrust Bearing ◽  
Hydrodynamic Lubrication ◽  
Governing Equations ◽  
Eddy Viscosity Model ◽  
Hydrodynamic Lubrication Theory ◽  
Made In

A theoretical analysis was made of the effects of the inclusion of inertia, viscous, and turbulence terms in hydrodynamic lubrication theory is applied to a thrust bearing. The solution to the governing equations is obtained by an iterative numerical method. An improved eddy viscosity model is employed to evaluate the turbulence term. Results are compared with existing measurements made in bearing models and also with other theoretical solutions. The contribution of inertia and viscous terms is discussed in light of the obtained results.

A Thermal Hydrodynamic Lubrication Theory for Hydrostatic Extrusion of Low Strength Materials

1976 ◽  
Vol 98 (2) ◽  
pp. 335-342 ◽  
Author(s):  
R. W. Snidle ◽  
B. Parsons ◽  
D. Dowson
Keyword(s):  
Plastic Deformation ◽  
Theoretical Analysis ◽  
Thermal Effects ◽  
Hydrodynamic Lubrication ◽  
Extrusion Process ◽  
Lubrication Theory ◽  
Lubricant Film ◽  
Hydrostatic Extrusion ◽  
Solid Friction ◽  
Hydrodynamic Lubrication Theory

The paper presents a theoretical analysis of hydrodynamic lubrication in the hydrostatic extrusion process which includes a consideration of thermal effects in the lubricant film arising from the work of plastic deformation. A Newtonian lubricant with an exponential pressure-temperature-viscosity relationship has been assumed and allowance has been made for the effects of redundant deformation of the worked material. The results of the theory are compared with those from previous isothermal and solid friction theories.

scholarly journals Propeller Excitation of Longitudinal Vibration Characteristics of Marine Propulsion Shafting System

2014 ◽  
Vol 2014 ◽  
pp. 1-19 ◽  
Author(s):  
Ganbo Zhang ◽  
Yao Zhao ◽  
Tianyun Li ◽  
Xiang Zhu
Keyword(s):  
Natural Frequency ◽  
Thrust Bearing ◽  
Hydrodynamic Lubrication ◽  
Longitudinal Vibration ◽  
Axial Stiffness ◽  
Oil Film ◽  
Marine Propulsion ◽  
Hydrodynamic Lubrication Theory ◽  
Small Perturbation Method ◽  
Thrust Load

The submarine experiences longitudinal vibration in the propulsion shafting system throughout most of run. A transfer matrix model of the propulsion shafting system, in which the dynamic characteristics of oil film within thrust bearing are considered, is established to describe the dynamic behavior. Using hydrodynamic lubrication theory and small perturbation method, the axial stiffness and damping of oil film are deduced in great detail, followed by numerical estimation of the foundation stiffness with finite element method. Based upon these values of dynamic parameters, the Campbell diagram describing natural frequencies in terms of shafting rotating speeds is available, and the effect on the 1st natural frequency of considerable variations in thrust bearing stiffness is next investigated. The results indicate that the amplitude of variation of the 1st natural frequency in range of low rotating speeds is great. To reduce off-resonance response without drastic changes in propulsion shafting system architecture, the measure of moving thrust bearing backward is examined. The longitudinal vibration transmission through propulsion shafting system results in subsequent axial excitation of hull; the thrust load acting on hull is particularly concerned. It is observed that the measures of structural modification are of little benefit to minimize thrust load transmitted to hull.

A Model of Coherent Disturbances in Compressible Mixing Layers

2002 ◽  
Author(s):  
Hong Yang ◽  
Anatoli Tumin
Keyword(s):  
Turbulent Mixing ◽  
Large Scale ◽  
Eddy Viscosity ◽  
Mixing Layer ◽  
Governing Equations ◽  
Turbulent Mixing Layer ◽  
Eddy Viscosity Model ◽  
Temperature And Pressure ◽  
Mean Time ◽  
Theoretical Results

A theoretical model of harmonic perturbations in a compressible turbulent mixing layer is proposed. The model is based on the triple decomposition method. It is assumed that the instantaneous velocities, temperature, and pressure consist of three distinctive components: mean (time-averaged), coherent (phase-averaged), and random (turbulent) motion. The interaction between incoherent turbulent fluctuations and large-scale coherent disturbances is incorporated by the Newtonian eddy viscosity model. The governing equations for the coherent disturbances have the same form as in laminar flow with substitution of the Reynolds number and the Prandtl number by their turbulent counterparts. A slight divergence of the flow is also taken into account. Theoretical results and comparison with experimental data reveal the significance of interaction between the coherent and random constituents of the flow.

Design of Main Pump Motor’s Water Lubricated Bearing and Research on its Lubrication Performances

2012 ◽  
Vol 538-541 ◽  
pp. 1971-1974
Author(s):  
Xin Rong Wang ◽  
Xiao Hai Li ◽  
Ya Chao Cui ◽  
Li Hua Yang
Keyword(s):  
Carrying Capacity ◽  
Thrust Bearing ◽  
Working Condition ◽  
Hydrodynamic Lubrication ◽  
Thrust Bearings ◽  
Structure Of Water ◽  
Low Viscosity ◽  
Factors Influencing ◽  
Hydrodynamic Lubrication Theory ◽  
The Right

Water-lubricated thrust bearing is a key component of certain main pump motor. In this paper, the right structure of water-lubricated thrust graphite bearings is designed based on low viscosity hydrodynamic lubrication theory by combining the bearings running working condition, and the frictional accessory material is also determined by theoretical analysis and test. The factors influencing lubrication performances of water-lubricated thrust bearings are analyzed; the methods improving lubrication performances are put forward to guarantee that water-lubricated thrust graphite bearings have the good lubrication performances, good carrying capacity and longer work life.

An asymptotic theory for the turbulent flow over a progressive water wave

1987 ◽  
Vol 174 ◽  
pp. 69-80 ◽  
Author(s):  
S. J. Jacobs
Keyword(s):  
Phase Shift ◽  
Turbulent Flow ◽  
Growth Rates ◽  
Water Wave ◽  
Present Model ◽  
Governing Equations ◽  
Lower Growth ◽  
Phase Velocities ◽  
Eddy Viscosity Model ◽  
Wave Induced

The turbulent flow over a progressive water wave is studied using an eddy viscosity model. The governing equations are treated asymptotically for the case ε [Lt ] 1, where ε is the square root of a characteristic drag coefficient. A calculation of the phase shift between the wave-induced pressure perturbation and the surface elevation shows that the phase shift is induced by a term in the gradient of the Reynolds stress. Growth rates are determined, and are shown to agree well with observations for the most rapidly amplifying waves. However, the present model and previous turbulence calculations are found to provide significantly lower growth rates than those measured by Snyder et al. (1981) for waves with phase velocities comparable to the wind speed.

The linear response of turbulent flow to a volume force: comparison between eddy-viscosity model and DNS

2016 ◽  
Vol 790 ◽  
pp. 104-127 ◽  
Author(s):  
S. Russo ◽  
P. Luchini
Keyword(s):  
Turbulent Flow ◽  
Linear Response ◽  
Eddy Viscosity ◽  
Bottom Topography ◽  
Viscosity Model ◽  
Correct Result ◽  
Mean Velocity ◽  
Volume Force ◽  
Eddy Viscosity Model ◽  
External Volume

We identify a benchmark problem simple enough that it can be solved both by an eddy-viscosity model and by direct numerical simulation: this is the linear response of a turbulent flow’s mean-velocity profile to an external volume force. An example of such a force was found in a study of the perturbation induced by bottom topography by Luchini & Charru (J. Fluid Mech., vol. 656, 2010, pp. 337–341). On the other hand, a modification of the method by Quadrio & Luchini (Proceedings of the IX European Turbulence Conference, Southampton, UK, 2002, pp. 715–718) and Luchini et al. (Phys. Fluids, vol. 18, 2006, 121702) to compute the linear impulse response of a wall-bounded turbulent flow allows the response to a volume force to be computed directly. The comparison exhibits significant differences and suggests that there might be fundamental obstacles to designing an eddy-viscosity model that provides the correct result.

A Model of the Turbulent Burst Phenomenon: Fully Developed Transitional Turbulent Flow Between Parallel Plates

1982 ◽  
Vol 49 (4) ◽  
pp. 697-703 ◽  
Author(s):  
L. C. Thomas ◽  
H. M. Kadry
Keyword(s):  
Turbulent Flow ◽  
Eddy Viscosity ◽  
Wall Region ◽  
Parallel Plates ◽  
Burst Frequency ◽  
Mean Velocity ◽  
Eddy Viscosity Model ◽  
Region Model ◽  
High Reynolds ◽  
Turbulent Burst

An analysis is presented for fully developed transitional turbulent flow between parallel plates that features the use of a turbulent burst model for the important wall region. Model closure is accomplished by the specification of the mean burst frequency and, for moderate to high Reynolds numbers, by matching with a classical eddy viscosity model for the turbulent core. Predictions obtained for friction factor and mean velocity distribution are compared with experimental data for fully developed transitional turbulent flow in a channel with large aspect ratio. Predictions are also developed for the eddy viscosity within the wall region for transitional turbulent conditions.

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