Abstract
This paper addresses the analytical evaluation of dynamic pressures and forces produced by the lubricant in a lubricated long journal bearing under dynamic loading. An evaluation of accuracy of the widely adopted Ott’s solution is conducted. The results show that when the journal center is moving toward the center of the bearing and the eccentricity ratio is high, the force formulation according to Ott’s solution give inaccurate results. Differences as high as 93% is found between Ott’s analytical solution and the numerical solution for certain conditions. Starting from Reynolds partial differential equation of lubrication theory, a new formulation for the dynamic characteristics of lubricated long journal bearing under dynamic loading is presented. The analytical integrations were conducted utilizing the Sommerfeld variable. The lubricant forces calculated at certain instants of time showed exact match with the numerical solution, which is not the case with Ott’s solution. The pressure distribution in the new formulation showed a slight difference compared to the Ott’s solution. The methodology presented in the new formulation to calculate the zero pressure angles at any instant of time showed exact match with the numerical results regardless of sharp changes in the pressure between the positive and negative regions. The new formulation is utilized in evaluating the transient and steady state characteristics of lubricated long journal bearing under unidirectional constant load and the results arc compared with the Ott’s solution.
