Isabelle Pierre

Bio: Isabelle Pierre is an academic researcher from University of Poitiers. The author has contributed to research in topics: Bearing (mechanical) & Fluid bearing. The author has an hindex of 1, co-authored 1 publications receiving 67 citations. Previous affiliations of Isabelle Pierre include Électricité de France.

Thermohydrodynamic Behavior of Misaligned Plain Journal Bearings: Theoretical and Experimental Approaches

Abstract: Hydrodynamic journal bearings are essential components for supporting and guiding the rotating shafts of high-speed machinery. Manufacturing defects in assembly or thermal distortions may introduce problems during running, such as misalignment. The destructive effects of this kind of running problem have justified the development of a numerical model to predict the bearing operating characteristics under steady-state conditions. The present work presents in detail the three-dimensional thermohydrodynamic approach adopted in this study in order to consider the thermal field variations. This model also includes lubricant film rupture and reformation phenomena by conserving the mass flow rate. In addition, an experimental validation is made by comparison with measurements carried out on our test device for various operating conditions and misalignment torques. The influence of misalignment direction is also investigated by considering numerical and experimental approaches used in the study of bearing behavio...

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

Abstract: 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 them to being widely used in industry. These mechanical components tend to be subjected to numerous start-ups 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, firstly, 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 (THD) one. The wear after more than 2,000 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, 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 180° and reaching nearly 9 μm. 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.Copyright © 2006 by ASME

On the Characteristics of Misaligned Journal Bearings

Abstract: Journal bearing misalignment arise generally from the shaft deformation under load, deflection of the shaft, manufacturing and assembly errors, improper installation, and asymmetric loading. During operations, misalignment has a considerable effect on the static and dynamic performances. It could cause wear, vibration and even system failure. In this article, a literature review of misalignment of the journal bearings is presented. The basic theory for the misalignment and some results for the circular journal bearing are also presented to show the general trends of the misalignment.

A new method for studying the 3D transient flow of misaligned journal bearings in flexible rotor-bearing systems

Abstract: The effects of journal misalignment on the transient flow of a finite grooved journal bearing are presented in this study. A new 3D computational fluid dynamics (CFD) analysis method is applied. Also, the quasi-coupling calculation of transient fluid dynamics of oil film in journal bearing and rotor dynamics is considered in the analysis. Based on the structured mesh, a new approach for mesh movement is proposed to update the mesh volume when the journal moves during the fluid dynamics simulation of an oil film. Existing dynamic mesh models provided by FLUENT are not suitable for the transient oil flow in journal bearings. The movement of the journal is obtained by solving the moving equations of the rotor-bearing system with the calculated film pressure as the boundary condition of the load. The data exchange between fluid dynamics and rotor dynamics is realized by data files. Results obtained from the CFD model were consistent with previous experimental results on misaligned journal bearings. Film pressure, oil film force, friction torque, misalignment moment and attitude angle were calculated and compared for misaligned and aligned journal bearings. The results indicate that bearing performances are greatly affected by misalignment which is caused by unbalanced excitation, and the CFD method based on the fluid-structure interaction (FSI) technique can effectively predict the transient flow field of a misaligned journal bearing in a rotor-bearing system.