Simulation of the air-oil mixture flow in the scavenge pipe of an aero engine using generalized interphase momentum exchange models

Understanding the flow in aero-engine lubrication systems forms an essential part of future designs for aero-engines. This especially applies to scavenge pipes which contain a complex two-phase flow formed by the interaction of sealing airflow and lubrication oil. In the last decade, two phase flows in pipes are increasingly modeled and simulated with 3D Computational Fluid Dynamics (CFD) codes. One of the major challenges is to approximate the different flow morphologies developed (bubbly, stratified, annular, slug, e.t.c.) using a unified CFD model without increasing prohibitively the computational cost. This paper presents a methodology implementing empirically derived generalized interphase momentum exchange models for modeling and simulation of the two phase flow of air and oil in the scavenge pipe of an aero-engine. The advantage of the proposed approach is the simplicity of the computational model which depends mainly on the assumed bubble diameter. Simulation results are presented and discussed for an experimental study performed at MTU Aero Engines facilities. This work is part of the European Union funded research program ELUBSYS (Engine LUBrication System TechnologieS) within the 7th EU Frame Program for Aeronautics and Transport.