Modelling of an Aero-Engine Bearing Chamber Using Enhanced CFD Technique

Abstract

This manuscript presents the application of an improved CFD methodology to simulate the scavenge system film flow phenomena in a real aero engine bearing chamber environment i.e. influence of seals and rotational shaft. Near the scavenge off-take, the usual thin film approach is not valid due to the occurrence of relative thick films (up to 5mm, comp. [1]) where film internal dynamics become very important. Therefore, other multiphase modelling techniques need to be explored. Young and Chew suggest in [2] that the Volume Of Fluid (VOF) method is the most suitable technique for air/oil system applications. Hashmi et al. reported in [3] that this free surface method for shear driven thick wall films in the bearing chamber environment needs additional provisions for turbulence modelling. Accordingly, a simple correction is made to the k–ε RNG turbulence model to improve the simulation results. The improved CFD methodology is applied to an engine representative geometry and proves to be robust and computationally efficient. The test conditions in the simulation was chosen in a way to avoid any droplet stripping from the film surface. It is shown that the applied methodology together with the correction in the turbulence modelling prove to play a vital role for a good comparison with experimental data. After validation the simulation results are used to describe the flow phenomena which occur in the bearing chamber for the investigated condition. The introduced CFD modelling technique shows large potential for the development and trouble shooting purposes in the industrial environment.