Toms effect was investigated experimentally and theoretically in journal bearings, that is, friction reduction in turbulent journal bearings by dilute polymer solution.
Experiments were carried out varying polymer molecular weight or bearing clearance. Through the visulization of flow pattern, the effect of polymer moleculars on the Taylor instabilities was examined in a journal bearing.
K-εmodel was proposed theoretically for flows with and without friction reduction in a journal bearing.
Base oil was used as solvent, and PIB was used as polymer.
Frictional torque was measured, and the variation of friction coefficient with Reynolds number was found.
The friction reduction increased as increasing polymer concentration, increasing molecular weight or decreasing radial clearance. The frictional torque and intencity of vortex flows by polymer solution was reduced compared with base oil. The prediction of the K-εmodel was in good agreement with the result of the experiment carried out with base oil. In the prediction of the K-εmodel, frictional torque tended to decrease when friction reduction was applied. This tendency was similar to the result of experiment when polymer was present.
