Oil Scoop Simulation and Analysis Using CFD and SPH

Abstract

The process of rotating scoops capturing oil coming out of a stationary jet nozzle was simulated with CFD (Computational Fluid Dynamics) and SPH (Smoothed Particles Hydrodynamics). The aim was to determine the efficiency of the oil capture, and the effects of varying parameters such as angular velocity of the scoops, the speed and direction of the oil jet and arrangement of the oil jets (in case of more than one jet). This configuration is found in engine cooling and/or lubricating systems: where oil scoops are used to deliver the oil to the places where direct injection is not possible. In CFD both two- and three-dimensional geometries were used; the models were then run using the Volume of Fluid method with the SST k-ω model. SPH is a meshless Lagrangian method for flow simulation, where the fluid is represented by particles. In addition to the conventional SPH formulation, three main highlights were introduced in the current work: the rotating ghost particles (representing the scoops), the particle collision model (Korzilius et al., 2014) and source and sink particles (representing the oil coming out from the nozzle and captured at the scoops respectively). The simulations allowed for the observation of the free surface of the oil jet (before, during, and after cutting of the jet by the blade), the pressure and velocity fields for the air and oil, and the efficiency of the system, defined as the ratio of oil outflow (via scoops) and inflow. This is a comparative study between CFD and SPH, where SPH is explored for a lubrication of a high-speed rotating component. The results of CFD and SPH, in particular the oil free surface and the efficiency, were then compared and validated with experimental results, demonstrating good agreement. The setup and comparison of the results obtained with the described techniques are presented in this work.