NON-NEWTONIAN EFFECTS ON THE COASTDOWN PHENOMENON OF HYDRODYNAMIC JOURNAL BEARINGS

The behavior of a rotating system after its power supply is cut off is called the coastdown Phenomenon. An experimental investigation of the coastdown characteristics Was Carried out on a rotor rig, with differ ent types of lubricants including a Newtonian oil, a blend of ISOVG 32 and hydrogenated styrene isoprene, multigrade oils, and aqueous polym er solutions in a hydrodynamic journal bearing. The characteristics we re plotted in terms of deceleration vs. speed, which resembled the Str ibeck diagram of friction due to viscous drag. Thus, the apparent Stri bech diagrams of friction or the above oils were obtained by plotting the derived coefficient of friction against the reciprocal Sommerfeld number. Theoretical results were obtained through the solution of the governing Reynolds equation and energy equation, for Newtonian and cub ic law fluid models. The experimental results are compared with the re spective theoretical results for the case of friction in journal beari ngs lubricated with non-Newtonian fluids.