Obtaining Precise Churning Loss for a Gearbox Using Advanced Smoothed Particle Hydrodynamics 2019-01-0348

Last several decades of car design were a continuous and slow process. In recent years, due to the electrification of engines, the design approach requires fast adaptation/modification of old technologies to fit the upcoming requirements. Moreover, the new technologies need to be developed from scratch. One of the most important elements that has been radically changing in recent years is the drive transmission system. In order to help the fast development of novel powertrains, the ability to make fast and accurate Computational Fluid Dynamics (CFD) analysis is of high importance.

A vast majority of the commonly used CFD solvers are based on Eulerian approaches (grid-based). These methods are, in general, efficient with some drawbacks, e.g. it is necessary to additionally handle the interface or free-surface within computational cells. Promising alternatives to Eulerian methods are Lagrangian approaches which, roughly speaking discretizes the fluid instead of spatial domain. One of the most common methods of this kind is the Smoothed Particle Hydrodynamics (SPH), a fully Lagrangian, particle-based approach for fluid-flow simulations. One of its main advantages over the Eulerian techniques is no need for a numerical grid. Consequently, there is no necessity to handle the interface shape because it is directly obtained from the set of computational particles.

The current study analyzes advantages and drawbacks of applying the SPH approach to model the power train systems. Numerical simulations are performed on single gears to establish a standardized process and evaluate load-independent losses in gearboxes. Several scenarios are covered to show the differences in fluid flow behavior and effects on the churning loss, as well as further extensions of the model are discussed. Load independent losses such as churning and windage losses play a significant role in gearbox design, especially in automotive applications with high rotational speeds. The current study attempts to report advancements in churning losses computations using an innovative simulation approach that models the fluid-structure interactions using meshless methods.