Influence of Wear on the Behavior of a Two-Lobe Hydrodynamic Journal Bearing Subjected to Numerous Startups and Stops

2006 ◽  
Vol 129 (1) ◽  
pp. 205-208 ◽  
Author(s):  
J. Bouyer ◽  
M. Fillon ◽  
I. Pierre-Danos
Keyword(s):  
Experimental Data ◽  
Numerical Simulations ◽  
Low Cost ◽  
Hydrodynamic Pressure ◽  
Journal Bearings ◽  
Numerical Studies ◽  
Hydrodynamic Journal Bearing ◽  
The Many ◽  
Bearing Behavior ◽  
Theoretical Results

The behavior of the hydrodynamic journal bearings is now very well known because of the many experimental and numerical studies that have been carried out on the topic. This interest in two-lobe journal bearings is due to the fact that their simplicity, efficiency, and low cost have led to them being widely used in industry. These mechanical components tend to be subjected to numerous startups and stops. During transient periods, direct contact between the journal and bearing induces high friction in the lubricated contact and hence wear of the lining. The aim of this work is, first, to present experimental data obtained on a journal lobed bearing subjected to numerous starts and stops. Then, a comparison is made between the measured bearing performance and numerical results, these being obtained on the assumption that the regime is a thermohydrodynamic one. The wear after more than 2000 cycles was measured and used to generate numerical simulations. The aim here was to compare experimental data with theoretical results. It was observed that hydrodynamic pressure increases, whereas the temperature at the film/bush interface slightly decreases on both the upper and lower lobes. These trends are confirmed by the numerical simulations, with theoretical results being very close to experimental data. The final value for wear was measured, the maximum being found to be located at an angular coordinate of 180deg and reaching nearly 9μm. The present study demonstrates that, for the case studied, while the bearing behavior is clearly affected by wear, the bearing still remains useable and safe.

Thermal Behavior and Friction in Journal Bearings

1970 ◽  
Vol 92 (3) ◽  
pp. 373-380 ◽  
Author(s):  
Al. Nica
Keyword(s):  
Experimental Data ◽  
Thermal Behavior ◽  
Heat Dissipation ◽  
Journal Bearings ◽  
Friction Torque ◽  
Operating Characteristics ◽  
Lubricant Flow ◽  
Theoretical Predictions ◽  
Theoretical Results ◽  
Good Agreement

This paper deals with friction and the field of temperature in the lubricant film of journal bearings. Theoretical results regarding the thermal behavior are checked with experimental data and good agreement is found. Emphasis is put on the variation of temperature and lubricant flow with the operating characteristics of the bearing and it is seen that theoretical predictions for minima of friction torque are backed by temperature measurements. Further on, the friction torque and the mechanism of heat dissipation in bearings are dealt with, in order to verify the assumptions used in the calculation schemes. The means of efficiently cooling the bearing are also discussed, as well as the part played by the divergent zone in this process.

THD Analysis of High Speed Heavily Loaded Journal Bearings Including Thermal Deformation, Mass Conserving Cavitation, and Turbulent Effects

1999 ◽  
Vol 122 (3) ◽  
pp. 597-602 ◽  
Author(s):  
Chao Zhang ◽  
Zixia Yi ◽  
Zhiming Zhang
Keyword(s):  
Experimental Data ◽  
Flow Rate ◽  
High Speed ◽  
Thermal Deformation ◽  
Numerical Solutions ◽  
Journal Bearings ◽  
Eccentricity Ratio ◽  
Temperature Distributions ◽  
Theoretical Results

Theoretical and experimental THD analyses of high speed heavily loaded journal bearings are presented. Numerical solutions include thermal deformation, mass conserving cavitation and turbulent effects. The pressure and temperature distributions, the eccentricity ratio, and the flow rate are measured. Agreement between theoretical results and experimental data is satisfactory. [S0742-4787(00)00803-1]

scholarly journals A model for the effect of bulk liquid viscosity on cavitation bubble dynamics

2017 ◽  
Vol 19 (31) ◽  
pp. 20635-20640 ◽  
Author(s):  
Yang Shen ◽  
Kyuichi Yasui ◽  
Tong Zhu ◽  
Muthupandian Ashokkumar
Keyword(s):  
Experimental Data ◽  
Numerical Simulations ◽  
Cavitation Bubble ◽  
Bubble Dynamics ◽  
Single Bubble ◽  
Bulk Liquid ◽  
Liquid Viscosity ◽  
Single Bubble Dynamics ◽  
Theoretical Results

The effect of bulk liquid viscosity on single bubble dynamics has been investigated using numerical simulations. The theoretical results obtained are supported by the published experimental data.

scholarly journals A method to enrich experimental datasets by means of numerical simulations in view of classification tasks.

2021 ◽  
Author(s):  
Damiano Lombardi ◽  
Fabien Raphel
Keyword(s):  
Numerical Simulations ◽  
A Priori ◽  
Industrial Applications ◽  
Main Question ◽  
Science And Engineering ◽  
Numerical Studies ◽  
Nearest Neighbours ◽  
Classification Tasks ◽  
Priori Information ◽  
Theoretical Results

Classification tasks are frequent in many applications in science and engineering. A wide variety of statistical learning methods exist to deal with these problems. However, in many industrial applications, the number of available samples to train and construct a classifier is scarce and this has an impact on the classifications performances. In this work, we consider the case in which some a priori information on the system is available in form of a mathematical model. In particular, a set of numerical simulations of the system can be integrated to the experimental dataset. The main question we address is how to integrate them systematically in order to improve the classification performances. The method proposed is based on Nearest Neighbours and on the notion of Hausdorff distance between sets. Some theoretical results and several numerical studies are proposed.

On the Stability of a Rigid Rotor in Finite Porous Journal Bearings With Slip

1986 ◽  
Vol 108 (2) ◽  
pp. 190-194 ◽  
Author(s):  
Ajit Kumar Chattopadhyay ◽  
B. C. Majumdar
Keyword(s):  
Experimental Data ◽  
Finite Length ◽  
Velocity Slip ◽  
Journal Bearings ◽  
Rigid Rotor ◽  
The Stability ◽  
Theoretical Results

This investigation deals with the stability characteristics of oil filled porous journal bearings of finite length and with velocity slip. The stability curves are drawn for different slip parameters, eccentricity ratios, slenderness ratios, and in the absence of any experimental data, the theoretical results for the solid bearings obtained by this analysis have been compared with the available results of solid bearing.

scholarly journals Transformations of actinides fission product yields due to post scission emission of nuclear particles:232Th

2021 ◽  
Author(s):  
V.T. Maslyuk ◽  
O.O. Parlag ◽  
M.I. Romanyuk ◽  
O.I. Lendyel ◽  
O.M. Pop
Keyword(s):  
Experimental Data ◽  
Fission Product ◽  
Fission Products ◽  
Product Yields ◽  
Fission Fragments ◽  
Charge Distributions ◽  
Fission Product Yields ◽  
Symmetric Fission ◽  
The Many ◽  
Theoretical Results

The "many ensembles" method was proposed to investigate the influence of nuclear particles' post-scission emission on mass and charge distributions of fission products. The post scission approximation had been used; each of these ensembles consists of the fission fragments after emission of chains of different lengths, both the beta (±β) particles and neutrons. The theory allows one to find the most probable two fragment clusters of fission products and study their evolution after the post-scission emission of nuclear particles. The isotope <sup>232</sup>Th was chosen as an example, the fission fragments of which are intensively studied in the experiment. It is shown that the post-scission emission of nuclear particles eventually leads to the convergence of the asymmetric peaks, which looks like enhanced symmetric fission mode over asymmetric one for fission product yields. A comparison of the theoretical results and experimental data for the <sup>232</sup>Th fission fragments indicates their satisfactory matching.

COMPARISON OF NUMERICAL SIMULATIONS WITH EXPERIMENTAL DATA FOR VERTICAL ANNULAR AND CHURN GAS-LIQUID FLOWS

2020 ◽  
Author(s):  
Larissa Steiger de Freitas ◽  
Marcus Vinícius Canhoto Alves ◽  
Rafael Rodrigues Francisco
Keyword(s):  
Experimental Data ◽  
Numerical Simulations ◽  
Liquid Flows

scholarly journals Reactivity in social scientific experiments: what is it and how is it different (and worse) than a Placebo effect?

2021 ◽  
Vol 11 (2) ◽  
Author(s):  
María Jiménez-Buedo
Keyword(s):  
Experimental Data ◽  
Conceptual Framework ◽  
Placebo Effect ◽  
Placebo Effects ◽  
Causal Inferences ◽  
Scientific Experiments ◽  
Social Scientific ◽  
The Many ◽  
Definition Of ◽  
In Virtue Of

AbstractReactivity, or the phenomenon by which subjects tend to modify their behavior in virtue of their being studied upon, is often cited as one of the most important difficulties involved in social scientific experiments, and yet, there is to date a persistent conceptual muddle when dealing with the many dimensions of reactivity. This paper offers a conceptual framework for reactivity that draws on an interventionist approach to causality. The framework allows us to offer an unambiguous definition of reactivity and distinguishes it from placebo effects. Further, it allows us to distinguish between benign and malignant forms of the phenomenon, depending on whether reactivity constitutes a danger to the validity of the causal inferences drawn from experimental data.

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