Numerical simulation on the oil capture performance of the oil scoop in the under-race lubrication system

Abstract

The under-race lubrication system providing a moderate amount of oil to high-speed bearings is one of the key factors to ensure its good lubrication and cooling. To investigate the oil capture performance of the oil scoop, a complete numerical calculation model was established, and unsteady simulations of oil–gas two-phase flow inside the under-race lubrication system were carried out. The results indicate that the oil capture efficiency increases first and then decreases with increasing rotating speed at different oil jet velocities. The ratio of the rotating Reynolds number of the oil scoop to the Reynolds number of the oil jet corresponding to the maximum oil capture efficiency changes linearly with oil jet velocity. There are three variation trends of oil capture efficiency at different rotating speeds with the increase of oil jet velocity: monotonically decreasing, first increasing, and then decreasing and monotonically increasing. However, the amount of oil captured by the oil scoop increases monotonically under all operating conditions. The effect of oil temperature on oil capture efficiency is mainly due to the change of dynamic viscosity of the oil. The oil capture efficiency can be improved by appropriately increasing the oil temperature within a certain temperature range.

Numerical and Experimental Investigations to Assess the Impact of an Oil Jet Nozzle with Double Orifices on the Oil Capture Performance of a Radial Oil Scoop

“…Figure 4 compares the variations in captured oil mass flow rate over time obtained from the 2D and 3D numerical simulations, where the height of the cross-section in the 2D numerical simulation is 1 m. It can be seen that the variation trends of the captured oil mass flow rate obtained using the 2D and 3D numerical simulations are similar, but the oil mass flow rate values are different. The sum of the total mass outflow is divided by the sum of the inflow of the oil jet nozzle to obtain the oil capture efficiency [8,16]. Figure 5 compares the oil capture efficiency obtained from the numerical simulations with the experimental results.…”

“…When the oil velocity was in the range of 10-30 m/s, the oil capture efficiency presented three kinds of changes in the process of gradually increasing the rotational speed: a monotonic decline, an initial increase and then a decrease, and a monotonic increase. However, the amount of captured oil, which is determined by the oil capture efficiency and the flow rate of the oil supply, increased monotonically under all operating conditions [16]. Qin et al [17] experimentally studied the effects of rotational speed, oil jet nozzle diameter, and oil temperature on oil capture efficiency.…”

Oil-Air Distribution Prediction Inside Ball Bearing with Under-Race Lubrication Based on Numerical Simulation

“…With centrifugal force caused by high-speed rotation, oil is supplied into the bearing cavity through radial holes on the inner ring, achieving lubrication and cooling of the bearing. Compared to jet lubrication, under-race lubrication provides better lubrication and cooling effects for high-speed conditions and has been increasingly adopted in modern aero-engine [7].…”

Flow Characteristics of Liquid Jet in Transverse Shear Crossflow

“…Under the influence of centrifugal force and pressure, oil flows into the bearing cavity through the hole in the inner ring. A continuous oil column is observed during the oil collection process of the oil collector [1] and the oil discharge process of the bearing inner ring hole [2]. The flow characteristics of the oil column have a significant impact on the lubricating and cooling effects within the bearings [3].…”