Numerical Investigation on Fluid Flow of Gear Lubrication

Abstract

Several details of the mechanism of gear lubrication are still in doubt in spite of many decades of study of this subject. The focus of our work is the investigation of the mechanism by which oil † temperature variations affect gear idle rattle, which requires an understanding of the distributions of lubricant and heat within a gearbox. This paper presents the findings of a study of lubricant flow in a simple model gearbox by means of CFD (Computational Fluid Dynamics) and its validation by a series of tests on a spur gear rig. The commercial CFD code Fluent is used to simulate the splash flow of lubricant, using the techniques of dynamic meshing and VOF (Volume of Fluid). Our model takes into account the effects on the distribution of gear lubricant of lubricant level and physical properties as well as rotational speed. The results demonstrate that the flow patterns are strongly influenced by all these variables. The predictions are validated by high-speed flow visualisations using high-resolution imaging in conjunction with a pulsed Cu-vapour laser light source and powerful white light source. The simulated fluid flows are in good qualitative agreement with the experimental visualisation. Estimates of the velocity of oil droplets from the images are compared with CFD predictions of the velocity in regions with high lubricant-phase-fraction resulting from lubricant splashing.

Numerical and experimental investigation of splashing oil flow in a hypoid gearbox

“…As shown in Figure 2, different methods have been applied in previous research to overcome this difficulty. Such methods include the nonteeth method (Lemfeld et al, 2007;Lemfeld & Frana, 2009), cutting-teeth method (Concli, Conrado, & Gorla, 2014; Lin et al, 2013;Moshammer et al, 2006) and gearseparation method (Dong, Lin, & He, 2012;Gorla et al, 2013;Li et al, 2009). The non-teeth method and cuttingteeth method eliminate all or part of the gear teeth and considerably change the gear geometry.…”

“…Lemfeld, Frana, and Unger (2007) studied the influence of the viscosity and sway angle on the oil distribution in a gearbox based on a simplified numerical model. Li, Versteeg, Hargrave, Potter, and Halse (2009) built a two-dimensional numerical model of a cylindrical gearbox to investigate the influences of the rotation speed, oil level and oil viscosity on the oil flow. Lin et al CONTACT Zijie Fan zjfan@tsinghua.edu.cn (2013) evaluated the lubrication state of a vehicle transmission using a simulation model and numerical results.…”

Detailed Investigations on the Oil Flow in Dip-Lubricated Gearboxes by the Finite Volume CFD Method

“…By using a two-dimensional finite volume (FV)-based CFD model, Li et al [9] analyzed the influence of rotational speed, immersion depth and oil viscosity on the oil distribution of a single-stage dip-lubricated gearbox. They asserted that the turbulence of the oil flow increases with the rotational speed and the oil fill level.…”

Experimental study of multiphase flow in a model gearbox

“…A particular insight into the fluid mechanics of gearboxes is attempted only in a fewer works. In papers [6][7][8] the studies were performed by using CFD and in papers [9,10] the CFD was used in combination with experiments. However the experimental data available in these works are very limited.…”