Multiphase Flow Simulation of the Oil Splashing during the Actuated Stage of an Innovative Axle Dry Braking System

This paper proposes the CFD simulation of the oil splashing within the discs’ chamber of a novel concept for axle dry braking system in off-highway vehicles. The system completely removes the lubricating oil from the discs’ chamber during the not-engaged configuration of the friction plates and it quickly restore it at the beginning of the braking stage when the discs’ cooling becomes crucial, thus ensuring a significant reduction of the power losses. The CFD analysis of the real component is performed to predict the efficiency of the system in terms of both the time needed to replenish the discs’ chamber when brake is actuated, and the hydraulic torque exerted by the splashing of the oil. The entire three-dimensional geometry of the domain is accurately discretized, and the multi-phase flow nature is addressed by means of the volume of fluid approach. Moreover, the two-equation realizable k-epsilon model is adopted to describe the turbulent characteristic of the flow under actual operating conditions. The results highlight the prompt response of the system at brake actuation in terms of discs’ lubrication and cooling and the amount of viscous energy losses produced by the rotating discs in the engaged configuration.