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With the objective of reducing windage power losses (WPL) in herringbone gears, WPL experiments involving the use of a shroud are conducted. Based on computational fluid dynamics (CFD), a herringbone gear numerical model is established. Based on the renormalization group (RNG) k–ε two-equation turbulence model and dynamic mesh technique, the features of flow field distribution around the gear; mechanism of reduction of WPL; shroud installation distance, coverage, and installation position; and influence law of WPL are analyzed. The CFD and experimental results, which exhibit good consistency, are used to infer the WPL behavior with respect to the input parameters. [ABSTRACT FROM AUTHOR]

In this study, we propose a computational fluid dynamics (CFD)-based method to study the lubrication and temperature characteristics of an intermediate gearbox with splash lubrication. A volume of fluid (VOF) multiphase model was used to track the interface between oil and air. A multiple reference frame (MRF) model was adopted to accurately simulate the movement characteristics of the gears, bearings, and the surrounding flow field. The thermal-fluid coupling computational model of an intermediate gearbox with splash lubrication was then established. Combined with experimental results, we verified that the lubricating oil temperature was below the limit requirement (<110 °C). The numerical results revealed that large amounts of lubricating oil were splashed onto the tooth surfaces near the gear meshing area. A large convective heat transfer coefficient corresponds to a low gear tooth surface temperature. The tooth surface temperature of the driving gear is higher than that of the driven gear. The distribution law of oil volume fraction of the bearing roller was jointly affected by the roller rotation direction and gravity. The convective heat transfer coefficient of the roller wall was largely related to the lubrication environment of the roller, including the oil distribution inside the bearing cavity and the flow rate. [ABSTRACT FROM AUTHOR]