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BEARING SYSTEM IN DYNAMIC LOADING INCLUDING SOLID CONTACT AND WEARING

Hilbert J. Wisbeck - Hilbert_J_Wisbeck@embraco.com.br
Adilson L. Manke - Adilson_L_Manke@embraco.com.br
EMBRACO, Empresa Brasileira de Compressores, Joinville, SC, Brasil

Alvaro T. Prata - prata@nrva.ufsc.br
Universidade Federal de Santa Catarina, Departamento de Engenharia Mecânica, Florianópolis, SC, Brasil.

In small reciprocating compressors for household applications the compressor shaft is placed vertically and supports a dynamic load associated to the transversal piston movement. Usually, for design purposes, the bearings are treated separately which precludes a precise description of the shaft orbit. In the present investigation both the main and the secondary journal bearings are modeled coupled and simultaneously, allowing for the shaft misalignment within the bearings. A new computation methodology is introduced and tested to determine the pressure distribution in both bearings via a direct procedure. Solid contact and wearing are both allowed to occur causing a significant impact on the frictional power and a minor effect on the shaft orbit.

Keywords: Lubrication, Bearing, Compressor, Friction, Wear.
 
 

Christian J. L. Hermes - hermes@nrva.ufsc.br
Álvaro T. Prata - prata@nrva.ufsc.br
Universidade Federal de Santa Catarina, Departamento de Engenharia Mecânica
Caixa Postal 476 - 88040-900 - Florianópolis, SC, Brasil

This paper presents a bidimensional model to describe the dynamical behavior of porous journal bearings. The model is based on the Reynolds' equation to calculate the pressure field in the oil film within the radial clearance. Darcy's Law is applied for the oil flow through the porous media. The journal dynamics is included in the formulation to determine the instantaneous journal orbit as the load varies. The partial differential equations were integrated numerically by the Finite Volume Method and the time-dependent ordinary differential equations were solved by a 4th order Runge-Kutta algorithm. The most attractive feature of this work is the validation of the short porous journal bearing theory (Morgan & Cameron, 1957) for dynamic operation.

Keywords: Porous Journal Bearings, Dynamic Load, Numerical Simulation