THERMOHYDRODYNAMIC SEIZURE - EXPERIMENTAL AND THEORETICAL-ANALYSIS

An experimental apparatus was designed and tested to study the thermal ly induced seizure in bearing. The setup consists of a simple, unloade d journal bearing configuration which lends itself to useful physical interpretation without the complexities that are present in the contro l of flow rates and eccentricity in a loaded journal bearing in which the clearance would vary with time. The motor was fitted with a curren t limiter which stopped the motor when the torque exceeded a certain l imit. Experiments revealed that with this particular system, the journ al speed undergoes a significant reduction with time until the operati on is halted by the current limiter, which signifies the occurrence of a seizure. The time of seizure is appreciably influenced by this beha vior. A parallel theoretical analysis, which takes into account the sp eed variation with time, was developed. The analysis includes the deri vation of the appropriate governing equations, which involve the trans ient analysis of flow velocity heat transfer, and thermomechanical exp ansion of the surfaces, together with the numerical solution. The resu lts of the simulations compare favorably to those obtained experimenta lly both in trend and magnitude. Finally, general behavior of the syst em in terms of its time-to-seizure characteristic is illustrated throu gh a series of parametric studies.