Both theoretical and experimental thermohydrodynamic problem of a finite length journal bearing is studied. The analysis takes into acount heat transfer between the film and both the shaft and the bush. Cavitation and lubricant recirculation are also taken into account. The experimental program is conducted on an original device to study the performance of a plain bearing. The pressure and the temperature distribution on bearing wall are measured along with the eccentricity ratio and the flows rate for different speeds and loads. The effect on the eccentricity ratio of differential dilatation is underlined. Agreement between theoretical results and experimental data is satisfactory.

A general THD theory and a comparison between theoretical and experimental results are presented. The generalized Reynolds equation, the energy equation in the film, and the heat transfer equation in the bush and the shaft are solved simultaneously. The cavitation in the film, the lubricant recirculation, and the reversed flow at the inlet are taken into account. In addition, the thermoelastic deformations are also calculated in order to define the film thickness. Good agreement is found between experimental data and theoretical results which include thermoelastic displacements of both the shaft and the bush.

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Finally, for practical purposes equally acceptable results can be obtained from conventional isoviscous data. This, however, is no substitute for a more detailed analysis if there is to be hope for getting better agreement between theory and experiments. References1 Ferron, J., Frene, J., and Boncompain, R., "A Study of the Thermohydrodynamic Performance of a Plain Journal Bearing. Comparison Between Theory and Experiments," ASME JOURNAL OF LUBRICATION TECHNOLOGY, Vol. 105, No. 3, July 1983. 2 Tonnesen, J., and Hansen, P. K., "Some Experiments on the Steady-StateCharacteristics of a Cylindrical Fluid Film Bearing Considering ThermalEffects," ASME JOURNAL OF LUBRICATION TECHNOLOGY, Vol. 103, 1981, pp The authors are to be congratulated for the accuracy of the results and for the good correlation between theory and experiments. It should also be pointed out that the data used for the calculation are clearly specified which permits to make some comparisons.Using the same theoretical approach as the one presented in [1 and 7] the discussers have developed a numerical program which is able to determine bearing performance for a multilobe journal bearing. The analysis takes into account heat transfer between the film and both the shaft and the bush; in the solids the heat transfer equation is assumed to be three-dimensional. Generalized Reynolds equation and energy equation are solved simultaneously in the film assuming that the viscosity varies at all points along and across the film. Cavitation and lubricant recirculation are also accounted for.The discussers used this program for the data presented in Table 2. The memory size needed was about 130 K octet and the computing time 27 seconds on a IBM 3081 to calculate the journal bearing performance for a given eccentricity ratio.Could the authors specify the memory size required and the computing time needed by their theoretical calculation?The theoretical results obtained by the discussers are compared in Fig. Dl to Fig. D4 to those given by the authors.Figures Dl and D2 show good agreement between theoretical and experimental circonferential bearing wall temperature. The discrepancies between theory and experiments noted in the rupture film zone are less important for the discussers' results than for the authors' results. Differences are also noted on the temperature in the grooves; these differences are due to the fact that the inlet flow temperature is introduced in [1, 7] by a step on the oil temperature. But this discontinuity is not very important because, as remarked by the authors, the inlet temperature has a limited influence on the film temperature in the pad. Figure D3 shows that the theoretical pressure curve obtained by the discussers is almost the same as the one obtained from Lund's theoretical analysis. Finally, Fig. D4 shows the variation of the eccentricity ratio versus load for two different speeds. The theoretical curves obtained by the discussers are in better agreement with experimental data than those given by the authors.In Fig. 5 the ...