PERFORMANCE OF HYBRID BEARINGS IN LAMINAR AND TURBULENCE REGIONS

Abstract

The objective of :,present work is to study the performance of hybrid bearing in both laminar and turbulent region. The finite element method is used to obtain the solution of lubricant flow field for both orifice and constant flow valve compensated hybrid bearing. The effect of turbulence on bearing performance has been studied in terms of pressure and shear Reynold's number. The static performance characticistics are presented in terms of maximum pressure, minimum fluid film thickness, bearing flow attitude angle and dynamic characteristics are presented in terms of stiffness coefficient, damping coefficient and threshold speed for different restrictor. It's been found that bearing performance is significantly affected in turbulent region as compared to laminar region. At a constant value of external load (Wo) and restrictor design parameter (Cs2), bearing performance charactristics,such as maximum pressure (''max) Attitude angle (0), Bearing flow,.. (Q) direct stiffness coefficient (S11) cross coupled stiffness coefficient (S12) direct damping coefficent (C11) increases with both turbulent paramenter REC and REP. However all the variation is more in case of REC than with REP. Cross coupled damping coefficent (C12) decreases with. both turbulent parameters. The value of h . increases with REC but reduces with REP. The effect min of REC is predominant on both the static and dynamic performance characteristic as compared to REP. The static and dynamic performance charateristics such as minimum film thickness (h mi), attitude angle (~), direct stiffness coefficient (S11), cross-coupled stiffness coefficent (S12), increases as speed parameter (Q) is changed form 0.5 to 1.0 in both laminar and turbulent region. However maximum pressure (P max), direct stiffness coefficient (S22) cross coupled stiffness coefficient (S21),direct damping coefficient (C22), cross-coupled damping ,coefficient (C12 = C21) and threshold speed, decreases as (0) is changed from 0.5 to 1. 0 . -. (