Thermohydrodynamic Seizure: Experimental and Theoretical Analysis

An experimental apparatus was designed and tested to study the thermally induced seizure in bearing. The setup consists of a simple, unloaded journal bearing configuration which lends itself to useful physical interpretation without the complexities that are present in the control of flow rates and eccentricity in a loaded journal bearing in which the clearance would vary with time. The motor was fitted with a current limiter which stopped the motor when the torque exceeded a certain limit. Experiments revealed that with this particular system, the journal speed undergoes a significant reduction with time until the operation is halted by the current limiter, which signifies the occurrence of a seizure. The time of seizure is appreciably influenced by this behavior. A parallel theoretical analysis, which takes into account the speed variation with time, was developed. The analysis includes the derivation of the appropriate governing equations which involve the transient analysis of flow velocity, heat transfer, and thermomechanical expansion of the surfaces, together with the numerical solution. The results of the simulations compare favorably to those obtained experimentally both in trend and magnitude. Finally, general behavior of the system in terms of its time-to-seizure characteristic is illustrated through a series of parametric studies.