Abstract
As it is widely employed in the aeronautical transmission system, a better understanding of the oil jet lubrication behavior is vital to determine the total system energy consumption. Firstly, this study presents related theoretical models such as the sum of oil jet resistance torque, impingement depth, and wetted area of the oil film for calibrating the physical characteristics of the impact of the oil jet on the gear flank. Then, in terms of the flow phenomenology of the liquid column for the oil jet impact on an isolated spur gear, a detailed transient and spatial flow field analysis becomes available, benefiting from an overset mesh method integrating with a volume-of-fluid (VOF) method. Furthermore, not only the oil jet resistance torque, but also the impingement depth as well as the spatial and temporal evolution of wetted surface by the oil film on the gear tooth given by numerical investigations were compared well with the theoretical calculations.
Highlights
Motivated by severe GHG emissions nowadays, the aircraft industry is committed to reducing energy consumption, thereby continuously improving the transmission efficiency of each gearing system in the aeroengine
The comparison indicated that the oil jet resistance torque is mostly caused by the power required to change the direction of the oil flow and reaccelerate it
A detailed investigation of the flow phenomenology of the jet flow impinging on the tooth surface of an isolated spur gear under oil jet lubrication is presented in this study
Summary
Motivated by severe GHG (greenhouse gas) emissions nowadays, the aircraft industry is committed to reducing energy consumption, thereby continuously improving the transmission efficiency of each gearing system in the aeroengine. The load losses of gears are tied to the friction behavior of gear mesh, namely a mechanical power loss, whereas the no-load losses are associated with motions of lubricant and air. The latter is far from negligible at high speeds [3]. For jet-lubricated gears, there are other losses—impulse power losses and windage power losses, without churning losses [8,9]. The impulse power losses are related to the momentum transfer when the high-speed oil stream injected from the oil jet nozzle impacts the gear tooth surface.
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