Development of fast and accurate Software of Dynamic Journal Bearings

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Usually calculated dynamic coefficient are stored as a database and the database is used in designing journal bearings. However, an amount of the data becomes larger with increase in number of parameters such as L/D ratio and bearing type. Therefore, in these cases, the use of database becomes almost impractical. This is the reason why we develop fast and accurate software for obtaining dynamic coefficients of journal bearings.? 1)Matrix Form of Reynolds Equation,(Expansion of Pressure by Orthogonal Functions). The method is applied to obtaining the static film forces of journal bearings. As this method works effectively when boundary lines are parallel to coordinate axes, a quasi-Reynolds boundary condition is introduced.Under this condition,the trailing boundary line is given by a straight line and the bulk flow across this line is ensured to be continuous. It is shown that so-called Reynolds condition can be satisfactorily approximated by the quasi-Reynolds condition, and the time required by the calculation is such less than that required by ordinary finite difference method.2)A Fast Method for Calculating Dynamic Coefficients of Finite Width Journal Bearings With Quasi Reynolds Boundary Condition. The method is applied to the dynamic problems of journal bearings.The derivatives of the film forces with respect to eccentricity ratio, attitude angle, and with respect to their time are obtained by small number of vector calculations after obtaining the statiefilm forces.3)On the Cross Terms of the Damping Coefficients of Finite Width Journal Bearings. The cross terms of the linear damping coefficients of finite width journal bearings are equal to each other i.e., Cxy=Cyx,the general approach for solving the Reynolds equation 1),2) is used.