Numerical Calculation of the Oil Flow in a Truck Rear Axle Transmission and the Influence of Gear-Induced Air Flow

Abstract

Abstract For the reliable operation of a gearbox, consistently sufficient lubrication of tooth contacts and bearings is necessary. Thus, gearbox oil flow plays an important role. Additionally, air flow may affect the oil flow in the gearbox. The state of the art indicates that Computational Fluid Dynamics (CFD) enables targeted support of the gearbox development process at an early stage. Computational time plays a prominent role in practical applications due to associated costs. The particle-based Smoothed Particle Hydrodynamics (SPH) shows great potential for time-efficient calculations, especially with a simplified single-phase modeling approach. This study examines the influence of gear-induced air flow on gearbox oil flow, focusing on a test gearbox to identify a suitable modeling approach for a truck rear axle transmission. The results indicate that for the investigated operating conditions, the gear-induced air flow only impacts gearbox oil flow at higher circumferential speeds. For lower circumferential speeds, a single-phase SPH yields good results with significantly reduced computation times compared to the two-phase SPH. Applying the single-phase SPH to the truck rear axle transmission and comparing numerical results with experimental findings demonstrates a reliable representation of the oil flow characteristics.