| With the development of modern machinery in the direction of large-scale, highspeed and high performance, there has always been a huge demand for efficient journalbearings with high performance in machines like steam turbines, centrifugalcompressors, pumps, and motors. Research on hydrodynamic journal bearing has beganto go deep into the fluid dynamic characteristic such as load capacity, stability,temperature rise, power loss and sliding sideways velocity and its’ effect andrequirement to three-dimensional wedge gap. In order to achieve the profile equation ofjournal bearing with excellent properties, a method of the shape optimization ofhydrodynamic journal bearing based on three-dimensional reverse was proposed in thispaper, which was used for optimized design of hydrodynamic journal bearing undercertain condition. The subject in this paper comes from the national fund project. Themain work and results are as follows:①The fast-optimization algorithm, genetic algorithm was selected as an effectivealgorithm of shape optimization for journal bearing, by consulting and studying a largenumber of literatures on the hydrodynamic journal bearing.②After the analysis for the theory of hydrodynamic lubrication, three-dimensionalsimulation was numerically conducted for the static characteristic and dynamiccharacteristic of the hydrodynamic journal bearing. The response analysis on the staticand dynamic characteristics of the hydrodynamic bearing was respectively processed byusing the finite difference program written by MATLAB. Comparing the results of theliteratures, we can conclude that using the finite difference program is correct andeffective.③A finite element mathematical model for journal bearings, possessing thegeneral film thickness equation based on integration theory of hydrodynamic bearingsprofiles was established by FLUENT and COMSOL Multiphysics respectively.Three-dimensional static characteristics simulation was numerically conducted forpressure distribution of the hydrodynamic journal bearing, the oil leakage and powerloss. Comparing CFD results with the numerical results, we can verify the accuracy ofthe theory of general film thickness equation and the feasibility of the numericalalgorithm. ④The three-dimensional model was established by increasing or reducing thenumber of discrete points of oil film equation. Then Aiming at load capacity and thepressure distribution, the reverse design was processed for the oil film distribution ofideal bearing by using genetic algorithm(GA) to obtain the profile equation ofhydrodynamic journal bearing. This method of transforming three dimensional space ofthe oil film thickness by using matrix transformation and integral was effectivelyapplied to the reverse design combination with genetic algorithm. Example analysisproved the accuracy and the feasibility of reverse design for hydrodynamic bearing.Taking results of reverse design as the initial design variables, the stability of journalbearing under a certain condition was optimized to improve the stability of bearingperformance. This optimization aimed at the critical instability of angular velocity andtook load capacity and minimum oil film thickness as constraints condition. Throughthe shape optimization, then the critical instability speed of the journal bearingoptimized was improved by33.45%. The research on the optimization to the stability ofjournal provides theory basis and data reference for the design of journal bearing. |
