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.
The French energy company EDF has experienced in the last years some problems in managing reactor coolant pumps (RCP) seals in operation. That’s why a thermo-elasto-hydrodynamical model of the seal has been developed. The present model is a steady two-dimensional approach so as to characterize the normal operating mode of the seal. Numerical results are successfully compared to experimental results of leak-flow rate. The influence of pressure drop and injection temperature is described. The influence of the conicity of the faceplates is underlined. The friction is introduced in the model in order to reproduce the hysteretic behavior of the seal. The development of this model leads to a better knowledge of the behavior of a critical component.
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