Paper 5: The Effect of Journal Misalignment on the Performance of a Journal Bearing under Steady Running Conditions

1966 ◽  
Vol 181 (2) ◽  
pp. 45-54 ◽  
Author(s):  
A. J. Smalley ◽  
H. McCallion
Keyword(s):  
Load Capacity ◽  
Full Range ◽  
Axial Direction ◽  
Friction Torque ◽  
General Validity ◽  
Load Line ◽  
Oil Flow ◽  
Method Of Solution ◽  
Two Parameters ◽  
Journal Misalignment

A method of solution is described in which the governing equation is modified to account for variations in the oil-film thickness in the axial direction owing to journal misalignment. The position of the journal is specified by means of its eccentricity at its mid-length and by two parameters defining the extent and direction of the misalignment. The pressure distribution is evaluated numerically, and the direct load, friction torque, oil flow, and couple arising from the misalignment of the journal are obtained by numerical integration. A full range of journal misalignment conditions is examined for two length-diameter ratios. Results are presented in the form of non-dimensionalized graphs, showing the variation of direct load and misalignment couple with the journal misalignment parameters described. The angle between the line of action of the misalignment couple and the load line is evaluated in each instance, and graphs are presented to show the variation of the performance parameters for a particular degree of misalignment with the direction of application of the couple. Results for the particular instances in which the couple is in line with or at right angles to the load line are extracted, and these are compared with published experimental results of other workers. Good agreement is obtained, and moreover it is shown that, in general, these are not the two extremes of misalignment. For these two conditions design charts are presented, whereby, from knowledge of the applied couple and direct load, the degree of misalignment and the resultant peak pressure parameter may be determined. Charts which illustrate the reduction in load capacity for a particular journal misalignment in the plane of the load are also presented. General validity is claimed for this method of exploring a relatively unexamined subject, and the results are considered by the authors to be a useful improvement on those obtained by previous analytical workers.

Effect of Transverse and Longitudinal Surface Waviness on the Operation of Journal Bearings

1972 ◽  
Vol 14 (3) ◽  
pp. 168-172 ◽  
Author(s):  
P. Shelly ◽  
C. Ettles
Keyword(s):  
High Speed ◽  
Load Capacity ◽  
Surface Waviness ◽  
Machining Processes ◽  
Finishing Process ◽  
Oil Flow ◽  
Method Of Solution ◽  
The Mean ◽  
Effect Of Surface ◽  
Bearing Friction

An analysis is made to evaluate the effect of surface finish produced by the two final machining processes of high speed aero boring and broaching. A finite difference method of solution is used in which the number of waves superimposed on the basic geometry is successively increased. A strong asymptotic trend was found for all bearing characteristics beyond a relatively small number of waves. It is found that the load capacity compared to a smooth bearing is reduced for both processes if the surface waviness is included as an addition to the film height. If the film thickness is assumed to extend to the mean wave height, the load capacity is increased. The effect of surface waviness becomes more pronounced at higher eccentricities or as the amplitude of the waviness is increased. The variation of bearing friction and oil flow is shown. It is concluded that neither finishing process would have a serious deleterious effect on journal bearing performance.

Prototype Design of a High-Speed Viscous Air Spindle

2008 ◽  
Author(s):  
Guido M. J. Delhaes ◽  
Anton van Beek ◽  
Ron A. J. van Ostayen ◽  
Robert H. Munnig Schmidt
Keyword(s):  
High Speed ◽  
Load Capacity ◽  
Axial Direction ◽  
Cylindrical Part ◽  
Traction Forces ◽  
Micro Cutting ◽  
Tool Holder ◽  
Air Spindle ◽  
Prototype Design

In this paper an innovative air driven spindle for micro cutting applications is presented. The spindle uses a viscous traction concept which has the advantage that the viscous traction forces can act directly on the cylindrical part of the tool, which makes the tool-holder redundant. Furthermore, the tool can be actuated in the axial direction within the housing. In this paper the concept of the viscous turbine, a design of a prototype spindle along with the traction and load-capacity of the spindle are discussed.

The Onset of Whirl Instability in Journal Bearings of Various Bore Shapes and Groove Sizes

1983 ◽  
Vol 105 (3) ◽  
pp. 342-352 ◽  
Author(s):  
M. Akko¨k ◽  
C. M. McC. Ettles
Keyword(s):  
Beneficial Effect ◽  
Load Capacity ◽  
Journal Bearings ◽  
Experimental Results ◽  
General Validity ◽  
Model Based ◽  
Linearized Model ◽  
Varying Viscosity

Experimental results are given for load capacity and whirl onset in journal bearings of circular, elliptical and offset halves bore shape. The general validity of the linearized model for predicting whirl is confirmed experimentally. Deviations between experimental results and the model, based on an isoviscous film, are attributed to the varying viscosity that occurs in practice, and to unavoidable excitation that gives rise to premature whirl. It is shown that increasing groove size has a destabilizing effect that can more than cancel the beneficial effect of preloading. This result is particularly relevant to the design of journal bearings in turbomachinery.

On the Stresses in a Rotating Disk of Variable Thickness

1952 ◽  
Vol 19 (3) ◽  
pp. 263-266
Author(s):  
Ti-Chiang Lee
Keyword(s):  
Variable Thickness ◽  
Stress Function ◽  
Hypergeometric Functions ◽  
Analytic Solution ◽  
Radial Distance ◽  
Rotating Disk ◽  
Numerical Examples ◽  
Confluent Hypergeometric Functions ◽  
Method Of Solution ◽  
Two Parameters

Abstract This paper presents an analytic solution of the stresses in a rotating disk of variable thickness. By introducing two parameters, the profile of the disk is assumed to vary exponentially with any power of the radial distance from the center of the disk. In some respects this solution may be considered as a generalization of Malkin’s solution, but it differs essentially from the latter in the method of solution. Here, the stresses are solved through a stress function instead of being solved directly. The required stress function is expressed in terms of confluent hypergeometric functions. Numerical examples are also shown for illustration.

Numerical analysis of the transient wear and lubrication behaviors of misaligned journal bearings caused by linear shaft misalignment

2021 ◽  
pp. 1-17
Author(s):  
Tianyou Yang ◽  
Yanfeng Han ◽  
Yijia Wang ◽  
Guo Xiang
Keyword(s):  
Numerical Model ◽  
Film Thickness ◽  
Contact Pressure ◽  
Elastic Deformation ◽  
Journal Bearing ◽  
Fluid Pressure ◽  
Axial Direction ◽  
Wear Depth ◽  
Wear Process ◽  
Journal Misalignment

Abstract The purpose of this study is to investigate the role of the misalignment journal, caused by journal elastic deformation, on the transient wear and mixed lubrication performances using a numerical model. In the numerical model, the transient geometry lubrication clearance considering the journal misalignment, the transient elastic deformation and the transient wear depth are incorporated to evaluate the transient film thickness during wear process. The evolutions, under different external loads, of the wear depth, wear rate, elastic deformation, film thickness, fluid pressure and contact pressure are calculated by the numerical model. Furthermore, the calculated results of the misaligned journal bearing are compared with those of the aligned journal bearing. The results show that the distributions of the wear depth, film pressure and elastic deformation are asymmetric along the axial direction and the peak values of them shift toward the back end when the journal misalignment is considered. The maximum wear depth, maximum fluid pressure, maximum contact pressure and maximum elastic deformation of the misaligned journal condition are significantly larger than those of the aligned journal condition.

Refined Model for Inclined Load Capacity of Suction Caissons

2003 ◽  
Author(s):  
Charles P. Aubeny ◽  
Seungwoon Han ◽  
J. Don Murff
Keyword(s):  
Load Capacity ◽  
Full Range ◽  
Skin Resistance ◽  
Cohesive Soil ◽  
Offshore Structures ◽  
Resistance Coefficient ◽  
Soil Conditions ◽  
Aspect Ratios ◽  
Inclination Angles ◽  
Suction Caissons

Suction caissons used as mooring anchors for offshore structures can, depending on design concept, be subjected to pullout forces ranging from nearly vertical for tension leg platforms, to intermediate inclination angles for taut mooring systems, to nearly horizontal for catenary moored systems. Hence, the ability to understand and predict suction anchor pullout resistance for a full range of load orientations is becoming of increasing importance. A previous paper by the authors presents a plastic limit analysis for estimating the load capacity of suction anchors over a full range of load inclination ranging from horizontal to vertical. The model was capable of predicting load capacity for various load attachment (padeye) depths, caisson aspect ratios, and soil undrained strength profiles that vary linearly with depth. Loading conditions are assumed to be undrained; therefore, a purely cohesive soil is assumed. The original analysis assumed full adhesion on the boundaries of the caisson; i.e., a skin resistance coefficient α equal to unity. However, actual values of this coefficient are less than unity, with specific values varying according to soil conditions and the method of caisson installation. To overcome the limitation of the original model, this paper presents a modified formulation that allows a skin resistance less than unity. The modified formulation develops an interaction relationship between vertical and horizontal soil resistance on the sides of the caisson that is applicable for any skin resistance conditions ranging from no to full adhesion.

Research on Turbulent Lubrication of Misaligned Journal Bearing Considering the Axial Motion of Journal

2019 ◽  
Vol 142 (2) ◽  
Author(s):  
Shaoyu Zhu ◽  
Jun Sun ◽  
Biao Li ◽  
Xiaoyong Zhao ◽  
Hu Wang ◽  
...  
Keyword(s):  
Load Capacity ◽  
Misalignment Angle ◽  
Axial Motion ◽  
Eccentricity Ratio ◽  
Movement Velocity ◽  
Film Pressure ◽  
Pressure Load ◽  
Lubrication Equation ◽  
Axial Movement ◽  
Journal Misalignment

Abstract Based on the coordinate transformation method, the generalized turbulent lubrication equation considering the axial motion of the journal is derived. The finite-difference method is used to solve the generalized turbulent lubrication equation. The variations of turbulent lubrication performance with axial displacement for different axial movement velocity of the journal, journal misalignment angle, and initial mid-plane eccentricity ratio are obtained. The results show that when the axial movement velocity of the journal increases, the mid-plane eccentricity ratio of the bearing and the minimum film thickness remain unchanged, the average Reynolds number, maximum film pressure, load capacity, frictional power, and side leakage increases. As the axial displacement of the journal increases, the greater the misalignment angle of the journal, the greater the degree of misalignment, maximum film pressure, load capacity, and misalignment moment of the bearing. The greater the initial mid-plane eccentricity ratio, the greater the degree of journal misalignment, maximum film pressure, load capacity, frictional power, and misalignment moment.

Computational Investigation of Flows and Pressure Fields Associated With Spur Gear Meshing

2014 ◽  
Author(s):  
Baydu C. Al ◽  
Kathy Simmons ◽  
Herve P. Morvan
Keyword(s):  
Power Transmission ◽  
Axial Direction ◽  
Spur Gear ◽  
Transient Pressure ◽  
Pressure Fields ◽  
Oil Flow ◽  
Power Transmission Systems ◽  
Compression And Expansion ◽  
Potential Applications ◽  
Computational Fluid Dynamics Cfd

The efficiency of power transmission systems is increasingly targeted with a view to reducing parasitic losses and improving specific fuel consumption (SFC). One of the effects associated with such parasitic losses is the successive compression and expansion of fluid within the cavities between teeth of a meshing gear pair as they rotate. This process is cyclic and there are multiple cavities compressed and expanded at the same time. During the meshing process the volume of the cavity between the teeth suddenly contracts and as a result pressure rises. The fluid is therefore expelled primarily in the axial direction (for spur gears) since this area is considerably larger compared to the backlash area. Once the cavity starts to expand fluid is drawn into the cavity between the teeth by the negative pressure. Besides the air flow in the gear box, the meshing point is of particular interest to the oil flow, since oil is typically injected at or upstream of the meshing point. Good understanding of such flows can be used to balance lubrication needs with the need to minimise the required oil volumes and parasitic losses. This paper proposes the use of Computational Fluid Dynamics (CFD) as a means to investigate the phenomenon. A simplified two-dimensional CFD approach has been developed to study flows and pressure fields associated with spur gear meshing. The influence of the rotational speed has been investigated. Good validation is shown for the transient pressure variation within the tooth space. The limitations and potential applications of the modelling strategy are then discussed.

AN ANALYSIS OF THE INFLUENCE OF JOURNAL’S HELICAL GROOVE ON THE WEAR AND LOAD CAPACITY OF THE SLIDING BEARING

Tribologia ◽  
2016 ◽  
Vol 268 (4) ◽  
pp. 191-199
Author(s):  
Leszek TOMCZEWSKI ◽  
Jarosław SĘP
Keyword(s):  
Load Capacity ◽  
Journal Bearings ◽  
Sliding Bearing ◽  
Hard Particles ◽  
Effective Reduction ◽  
Oil Flow ◽  
Helical Groove ◽  
Helical Grooves ◽  
Wear Tests ◽  
Contaminated Lubrication

The article presents the results of a sliding bearing with a helical groove on a journal. The studies included wear tests with contaminated lubrication oil and computer simulation of oil flow based on which the load capacity of a bearing was determined. The 7 bearings with different variants of helical grooves on journal bearings and classical bearings were studied. It was found that the helical groove on the journal makes it possible to significantly reduce the wear of the bearing in the case of oil contamination with hard particles. It was also shown that the groove on the journal ensures an effective reduction in wear and does not result in a significant reduction of load capacity.

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