5th International Conference on Mechanics and Materials in Design Chapter VII: Wear and Lubrication in Design 1 REF: A0735. 0708 THERMAL BEHAVIOR AND PERFORMANCE CHARACTERISTICS OF A TWIN AXIAL GROOVE JOURNAL BEARING AS A FUNCTION OF APPLIED LOAD AND ROTATIONAL SPEED F.P. Brito 1* , J. Bouyer 2 , M. Fillon 2 , and A.S. Miranda 1 1 Universidade do Minho, Departamento de Engenharia Mecânica, Guimarães, Portugal 2 Université de Poitiers, Laboratoire de Mécanique des Solides, Poitiers, France Email: (*) francisco@dem.uminho.pt SYNOPSIS An experimental investigation of the influence of applied load and rotational speed on the performance of a 100mm diameter plain journal bearing with two axial grooves located at ±90º to the load line has been carried out. The applied load varied from 2 to 10kN, whereas the rotational speed ranged from 1000 to 4000 rpm. Measurements of hydrodynamic pressure, temperature profiles at the oil-bush and oil-shaft interfaces, oil flowrate and minimum film thickness under steady state conditions have been performed and the results discussed. The operating conditions were found to affect significantly the temperature profile inside the bearing. At low eccentricity tests the maximum temperature occurred at the unloaded lobe of the bearing, with the downstream groove contributing poorly to bearing cooling. As eccentricity increased, a temperature increase in the loaded lobe of the bearing was observed, along with a temperature decrease in the unloaded lobe. At high eccentricities the downstream groove was found to contribute significantly to bearing cooling. Shaft temperature and oil outlet temperature did not seem to be significantly affected by increasing load. INTRODUCTION Journal bearings are widely used in rotating machinery, especially when shafts are submitted to both high speeds and heavy applied loads. Bearing thermal behavior and its effect on performance has been studied since several decades from now. In order to estimate bearing performance taking into account thermal effects, thermohydrodynamic (THD) theoretical models were developed focusing mainly on the single axial groove bearing geometry (Boncompain et. al, 1986, Mitsui, 1987, Pierre et. al, 2000). Existing theoretical models for twin groove bearings (Knight & Ghadimi, 1992, Ma & Taylor, 1994) still do not fully predict the thermal behavior of the bearing. The existence of an additional groove dramatically affects flow patterns and temperature profiles inside the bearing. It is still not fully understood the role of each oil supply groove on bearing cooling for different operating conditions. Experimental data is essential to fully understand the bearing behavior and to improve theoretical modeling. It is worth mentioning the experimental works of Lund & Tonnesen (1984), Fitzgerald & Neal (1992) and Ma & Taylor (1995) on twin axial groove journal bearings. The available experimental data concerning this bearing geometry is still rather limited. The present work aims to address this lack of information, presenting and discussing experimental results obtained for a span of operating conditions that include the less studied