Computational Fluid Dynamics Study of Oil Behavior in a Scoop, and Factors Affecting Scoop Capture Efficiency

Abstract

Due to the continuous reduction of engine sizes, efficient under-race lubrication becomes ever more crucial in order to provide sufficient amount of oil to various engine components. An oil scoop is a rotating component that captures oil from a jet, and axially redirects it to the bearing, providing under-race lubrication. Given the importance of lubrication in high-speed engine components, the efficiency study of under-race lubrication appliances receives rapidly growing demands from manufacturers and therefore is of great interest. This work provides description of computational fluid dynamics (CFD) methods that were found to be most accurate and efficient for a large parameter analysis of the scoop capture efficiencies. One of the main purposes of this paper is to demonstrate an optimal and validated computational approach to modeling under-race lubrication with a focus on oil capture efficiency. Second, to show which factors most influence the scoop capture efficiency. Additionally, simulations allow for the fluid behavior inside the scoop to be observed that cannot be visualized experimentally due to high speeds. An improved method of efficiency calculation is also presented and compared to existing methods (Cageao, P. P., Simmons, K., Prabhakar, A., and Chandra, B., 2019, “Assessment of the Oil Scoop Capture Efficiency in High Speed Rotors,” ASME J. Eng. Gas Turbines Power, 141(1), p. 012401; Korsukova, E., Kruisbrink, A., Morvan, H., Paleo Cageao, P., and Simmons, K., 2016, “Oil Scoop Simulation and Analysis Using CFD and SPH,” ASME Paper No. GT2016-57554.). Results of both two-dimensional (2D) and semi-three-dimensional (3D) simulations are provided. Both qualitative comparison of 2D with semi-3D simulations and quantitative comparison of 2D simulations with experiments (Cageao, P. P., Simmons, K., Prabhakar, A., and Chandra, B., 2019, “Assessment of the Oil Scoop Capture Efficiency in High Speed Rotors,” ASME J. Eng. Gas Turbines Power, 141(1), p. 012401) show consistency. Parameter study using 2D simulations is shown with variation of rotational scoop speed, jet angles, velocity ratio. Key results show that changes of the jet angle and velocity ratio can improve the scoop efficiency.