Thermal modelling of mixed non-Newtonian thermo-elastohydrodynamics in dry sump lubrication systems

Improved fuel efficiency is the primary objective in the optimization of modern drivetrain systems. Recently, the dry sump lubrication system is regarded as the lubrication system for high performance transmission systems. Dry sump lubrication enhances the system efficiency by reducing the churning losses, whilst providing sufficient lubrication for the tribological contacts. One of the most important aspects of any dry sump system is assessment of the thermal performance. The generated heat in the contacts should be dissipated through impinging jets and air-oil mist in the transmission casing in an efficient manner. The present work incorporates a tribological model and a 3D CFD model into a finite element model. The aim is to evaluate the quantity of generated heat in the lubricated gear pair contacts, as well as heat removal rate due to an impinging oil jet. Furthermore, the transient circumferential temperature distribution on gear surfaces is determined. This provides an accurate input temperature for the entrant lubricant in the gear teeth-pair contacts. Such an approach has not hitherto been reported in literature. To perform time-efficient system level analysis in the finite element model, extrapolated equations are obtained from a transient 3D CFD model using regression formulae.