Big End Bearing Losses with Thermal Cavitation Flow Under Cylinder Deactivation

Abstract

The paper presents a mixed thermo-hydrodynamic analysis of elliptic bore bearings using combined solution of Navier-Stokes, continuity and energy equations for multi-phase flow conditions. A vapour transport equation is also included to ensure continuity of flow in the cavitation region for the multiple phases as well as Rayleigh-Plesset to take into account the growth and collapse of cavitation bubbles. This approach removes the need to impose artificial outlet boundary conditions in the form of various cavitation algorithms which are often employed to deal with lubricant film rupture and reformation. The predictions show closer conformance to experimental measurements than have hitherto been reported in the literature. The validated model is then used for the prediction of frictional power losses in big end bearings of modern engines under realistic urban driving conditions. In particular, the effect of cylinder deactivation (CDA) upon engine bearing efficiency is studied. It is shown that bigend bearings losses contribute to an increase in the brake specific fuel consumption with application of CDA contrary to the gains made in fuel pumping losses to the cylinders. The study concludes that implications arising from application of new technologies such as CDA should also include their effect on tribological performance.

Study on Lubrication Performance of Journal Bearing with Multiple Texture Distributions

“…The effect of cavitation is not included in the analysis, either in terms of the single-phase analysis used or in the application of the boundary conditions, which is considered in a thermo-hydrodynamic analysis of the bearing with the CFD approach [17,18]. (b) In the XOZ plane, the journal bearing is meshed into m and n grids along the X and Z directions, where m is 10 M × and n is 10 N × .…”

Thermohydrodynamics of lubricant flow with carbon nanoparticles in tribological contacts

“…However, the majority impose certain predefined conditions at the points of lubricant film rupture and subsequent reformation. Shahmohamadi et al [15][16][17] have shown that the cavitation phenomenon in tribological contacts can be treated in a more accurate manner, using a two-phase flow model which predicts the occurrence of cavitation inherently without the need for imposing any predefined boundary conditions. For this purpose, the cavitation model proposed by Singhal et al [18] is used, where the growth of cavities are confined in a gap of finite size.…”

Efficiency of disengaged wet brake packs

“…where the number of spherical bubbles per unit volume and vapour pressure are assumed to be = 10 13 and 80 respectively. The bubble dynamics; growth and collapse is accounted for by the Rayleigh-Plesset equation.…”