Optimized design and CFD analysis of drag-reduction windshields for aviation spiral bevel gears

• CFD was used to analyze the flow field characteristics, such as the velocity field, pressure field, viscous force field, and turbulent kinetic energy distribution. • As the angle of the sector-shaped opening in the meshing area decreases, the windage of the gear pair decreases. • The oil drainage groove should be designed at a position where the included angle between the side of meshing out and the meshing center of the gear pair is 45°. • When the sector-shaped opening of the groove was small, the windage of the gear was also small, and the windage loss was the smallest when the groove opening angle was 10°. To reduce the windage loss caused by hydrodynamic behavior, this study optimizes the parameters of the windshield based on the analysis of the drag reduction mechanism of the windshield. CFD was used to analyze the flow field characteristics to study the influence of the windshield on the motion state of the fluid around the gears and to clarify the drag reduction mechanism of the windshield. The control variable method is adopted to study the influence of the opening at the meshing area of the gear pair and the oil drainage groove on the drag reduction effect of the windshield to optimize the design parameters of the windshield. The research results show that: the drag reduction effect is optimal when the windshield covers the three surfaces of the spiral bevel gear, and the windage power loss is minimized when the gap between the windshield and the gear surface is 1 mm. Without affecting the meshing motion of the gear pair, the smaller the meshing opening, the smaller the windage of the gear pair. When an oil drainage groove with a 10° sector-shaped opening is designed at the position where the included angle between the meshing-out side of the gear pair and meshing center is 45°, the drag reduction effect of the windshield is the best.