Theoretical and Experimental Determination of the Dynamic Characteristics of a Hydrodynamic Journal Bearing

1979 ◽  
Vol 101 (2) ◽  
pp. 129-137 ◽  
Author(s):  
D. W. Parkins
Keyword(s):  
High Speed ◽  
Journal Bearing ◽  
Previous History ◽  
Relative Magnitude ◽  
Data Logging ◽  
Linear Gradient ◽  
High Speed Data ◽  
Zero Values ◽  
Hydrodynamic Journal Bearing

This paper describes a theoretical and experimental investigation into the nonlinear characteristics of the eight coefficients which specify the lateral flexibility of a hydrodynamic journal bearing. Coefficient calculations allowed viscosity to vary with temperature, and pressure, and examined a range of positive and negative displacements and velocities. Experimental techniques have been developed in which coefficients were deduced from specially chosen, imposed vibration orbits arising from two mutually perpendicular external oscillating forces of variable relative magnitude and phase. Journal centre displacement and velocity were measured using high speed data logging equipment. Coefficients are defined in terms of a “zero” value and linear gradient. Using realistic criteria, measured coefficient non-linearity was found to be significant at eccentricity ratios greater than 0.78. Theory adequately predicted some “zero” values but not gradients. An improvement in the coefficient prediction may depend on the inclusion of some previous history dependent factors.

Linear stability analysis of finite hydrodynamic journal bearing under turbulent lubrication with coupled-stress fluid

2016 ◽  
Vol 68 (3) ◽  
pp. 386-391 ◽  
Author(s):  
Abhishek Ghosh ◽  
Sisir Kumar Guha
Keyword(s):  
Stability Analysis ◽  
Newtonian Fluid ◽  
High Speed ◽  
Journal Bearing ◽  
Slenderness Ratio ◽  
Linear Perturbation ◽  
Content Type ◽  
Hydrodynamic Journal Bearing ◽  
The Stability ◽  
Coupled Stress

Purpose Several researchers have observed that to satisfy modern day’s need, it is essential to enhance the characteristics of journal bearing, which is used in numerous applications. Moreover, the use of Newtonian fluid as a lubricant is diminishing day by day, and the use of Non-Newtonian fluids is coming more into picture. Furthermore, if turbo-machinery applications are taken into account, then it can be seen that journal bearings are used for high speed applications as well. Thus, neglecting turbulent conditions may lead to erroneous results. Hence, this paper aims to present focuses on studying the stability characteristics of finite hydrodynamic journal bearing under turbulent coupled-stress lubrication. Design/methodology/approach First, the governing equation relevant to the problem is generated. Then, the dynamic analysis is carried out by linear perturbation technique, leading to three perturbed equations, which are again discretized by finite difference method. Finally, these discretized equations are solved with the help of Gauss-Seidel Iteration technique with successive over relaxation scheme. Consequently, the film response coefficients and the stability parameters are evaluated at different parametric conditions. Findings It has been concluded from the study that with increase in value of the coupled-stress parameter, the stability of the journal may increase. Whereas, with increase in Reynolds number, the stability of the journal decreases. On the other hand, stability increases with increasing values of slenderness ratio. Originality/value Researches have been performed to study the dynamic characteristics of journal bearing with non-Newtonian fluid as the lubricant. But in the class of non-Newtonian lubricants, the use of coupled-stress fluid has not yet been properly investigated. So, an attempt has been made to perform the stability analysis of bearings with coupled-stress fluid as the advanced lubricant.

scholarly journals Determination of the optimal curvature of the turnout diverging track for HSR using dynamic analysis

2017 ◽  
Vol 2017 (10) ◽  
pp. 1-11
Author(s):  
Władysław Koc ◽  
Katarzyna Palikowska
Keyword(s):  
Dynamic Analysis ◽  
Analytical Method ◽  
High Speed ◽  
Extreme Points ◽  
Point Of View ◽  
High Speed Railway ◽  
Zero Values ◽  
Linear And Nonlinear ◽  
Selection Of

The paper presents an analytical method of identifying the curvature of the turnout diverging track consisting of sections of varying curvature. Such turnout is mainly applied on High Speed Railway. Both linear and nonlinear (polynomial) curvatures of the turnout diverging track are considered in the paper. Obtained solutions enable to assume curvature values at the beginning and end point of the geometrical layout of the turnout.The paper focus on a fundamental and unexplained so far issue connected with selection of the most favourable curvature section from the operational requirements point of view. In order to determine the optimal curvature a dynamic analysis has been carried out on the several representative cases. It has been indicated that, used in railway practice, clothoid sections with nonzero curvatures at the beginning and end points of the turnout should be verified. It has been proved that the turnout with nonlinear curvature reaching zero values at the extreme points of the geometrical layout is the most favourable.

Some Problems in Diesel Engine Research with Special Reference to Computer Control and Data Acquisition

1976 ◽  
Vol 190 (1) ◽  
pp. 137-151 ◽  
Author(s):  
M. Marzouk ◽  
N. Watson
Keyword(s):  
Diesel Engine ◽  
Data Acquisition ◽  
Heat Release ◽  
High Speed ◽  
Computer Control ◽  
Data Logging ◽  
Turbocharged Diesel Engine ◽  
Fuel Burning ◽  
Burning Rates ◽  
High Speed Data

SYNOPSIS A versatile computer-based testing and data acquisition facility developed to improve the speed and accuracy of engine research work is described. The role of computer-aided technology is illustrated through the discussion of two quite separate problems. Fuel burning rates (heat release diagrams) are the most basic measurement of combustion, yet highly sophisticated equipment and techniques are required to obtain accurate rate diagrams. The problem is illustrated through the derivation of heat release data by analysis of averaged and smoothed cylinder pressure diagrams from naturally aspirated and turbocharged diesel engines. Techniques developed for transducer mounting, choice of sampling interval, data-logging, processing, smoothing, etc. are presented. During transient conditions (e.g. sudden load chnages) a turbocharged diesel engine moves through operating regimes not normally encountered in steady state operation. Although empirical models have been used to prodict the transient response of these engines, only high-speed data-logging of many engine parameters during a transient will permit the development of more basic models. A fully instrumented turbocharged diesel engine has been run (under computer control) through a series of dynamic tests comprising load and speed demand changes, plus combinations of the two. The use of a computer controlled system allowed transients to be re-enacted with a very high order of accuracy following engine design changes. The high-speed data logging system enabled basic data, such as fuel burning rates, to be obtained for each cycle during the transient.

scholarly journals Optimum Groove Location of Hydrodynamic Journal Bearing Using Genetic Algorithm

2013 ◽  
Vol 2013 ◽  
pp. 1-13 ◽  
Author(s):  
Lintu Roy ◽  
S. K. Kakoty
Keyword(s):  
Genetic Algorithm ◽  
Sequential Quadratic Programming ◽  
Reynolds Equation ◽  
Journal Bearing ◽  
Mass Parameter ◽  
Load Flow ◽  
Flow Coefficient ◽  
Optimum Performance ◽  
Hydrodynamic Journal Bearing

This paper presents the various arrangements of grooving location of two-groove oil journal bearing for optimum performance. An attempt has been made to find out the effect of different configurations of two groove oil journal bearing by changing groove locations. Various groove angles that have been considered are 10°, 20°, and 30°. The Reynolds equation is solved numerically in a finite difference grid satisfying the appropriate boundary conditions. Determination of optimum performance is based on maximization of nondimensional load, flow coefficient, and mass parameter and minimization of friction variable using genetic algorithm. The results using genetic algorithm are compared with sequential quadratic programming (SQP). The two grooved bearings in general have grooves placed at diametrically opposite directions. However, the optimum groove locations, arrived at in the present work, are not diametrically opposite.

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