Recess Volume Fluid Compressibility Effect on the Dynamic Characteristics of Multirecess Hydrostatic Journal Bearings With Journal Rotation

Abstract

An analysis using finite difference method and small amplitude perturbation technique has been presented to evaluate the frequency dependent stiffness and damping coefficients of multirecess hydrostatic journal bearings including the effect of shaft rotation that results in hybrid operation. Recess volume fluid compressibility effect that results in the frequency dependent dynamic coefficients have been taken into account. Results for direct and cross stiffness coefficients, direct and cross damping coefficients are presented for a capillary compensated bearing with deep recesses. Frequency effects are shown in terms of dimensionless squeeze number (σ) for various recess volume parameters (γ) for different eccentricity ratios (ε0) and dimensionless speed parameter (Λ). It has been found that the dynamic coefficients are very drastically altered within a very useful range of frequency parameter (σ) and recess volume parameter (γ) resulting in increased direct stiffness coefficient and a substantially decreased direct damping coefficients. Journal speed parameter (Λ) results in substantial magnitude of cross stiffness and cross damping parameters. However, the cross damping coefficient is usually small in comparison to direct damping coefficient.