Design Of Journal Bearings In Reciprocating Compressors

Journal bearings in hermetic reciprocating compressors are analyzed experimentally as well as numerically. The motor current and the load applied to the bearing are measured to obtain the performance curve of the journal bearing, from which the critical Sommerfeld number is derived. In the numerical analysis, the Reynolds equation and equilibrium equations of the journal center are solved simultaneously with Newton-Raphson iterative method. Reynolds boundary condition is used for solving the Reynolds equation. Minimum film thickness and friction loss of the journal bearing are calculated under static loading condition. The universal value of the critical Sommerfeld number is obtained as a design criterion from the experimental result. The numerical analysis shows the way to suggest the optimum design of the journal bearing. NOMENCLATURE C clearance, m D bearing diameter, m e journal center position, m F load, N H friction loss, W h film thickness, m i motor current, A KT motor torque-current constant, N⋅m/A L bearing length, m p pressure, Pa R bearing radius, m S Sommerfeld number T torque, N⋅m t time, s U surface velocity average, m/s ∆U surface velocity difference, m/s X, Y rectangular coordinate system, m x circumferential coordinate, m z axial coordinate, m η dynamic viscosity, Pa⋅s μ friction coefficient ω rotational speed, rad/s