A Transient CFD Simulation of the Flow in a Test Rig of an Aeroengine Bearing Chamber

Abstract

In this paper, we present results for the application of an Eulerian-Lagrangian technique to the transient simulation of an oil film formation on the walls of an aeroengine bearing chamber. The flow of oil in an aeroengine bearing chamber consists of high speed oil droplets interacting with the bearing structures and flowing oil film. The situation in the chamber is highly rotational and consisting of sheared flow of air over oil. The bearing chamber may also be located in the vicinity of the combustion chamber. The oil provides lubrication and cooling of the hot structures. Modelling the flow in the bearing chamber is therefore complex. The Volume of Fluid (VoF) technique offers a potential platform to model droplet-film interaction; however, it requires fine mesh details to capture the flow to the droplet level. Such detailed resolution would not be practical for the complete chamber geometry because of the prohibitively expensive computational overhead requirements. A Lagrangian formulation is therefore proposed to represent the droplets as source terms in the Navier-Stokes equation while the film is represented using VoF. This effectively reduces the need to resolve the droplets explicitly. The predicted film formation pattern compares with experimental results.

Oil-Air Flow Between the Cage and Inner Race of an Aeroengine Bearing

“…These so-called thin film mod-els are based on lubrication theory with development for bearing chamber applications following chronolgically through Farrall et al [3], Williams [4], Kay et al [5] and Kakimpa et al [6]. Studies on more engine representative geometries, including [7][8][9] have investigated computationally the flow phenomenon inside the bearing chamber cavity. The recurring assumption in the models is that we understand the shedding characteristics of the oil from the bearing or in the simpler models, that the flow is a simple rimming flow.…”

A Coupled 1D Film Hydrodynamics and Core Gas Flow Model for Air-Oil Flows in Aero-Engine Bearing Chambers

“…In addition, this empirical data is often unavailable in the preliminary design stages. Recently, computational fluid dynamics has emerged as a valuable tool for obtaining more detailed insight into bearing chamber oil flow regimes as well as evaluating different design options in the early stages of design [5,4,6]. The main drawbacks of conventional CFD modelling is that it can be computationally expensive and hence unsuitable for the early stages of design during chamber sizing studies.…”

“…These flow regimes have been characterised by a number of experimental studies [1,2,3] and CFD simulations [4,5] of bearing chambers. Figure 1 illustrates the flow within a typical aero-engine bearing chamber flow.…”

A Computational Fluid Dynamics Simulation of Oil–Air Flow Between the Cage and Inner Race of an Aero-engine Bearing

“…One of the justifications for understanding the flow inside the bearing is the need for more accurate boundary conditions for our existing bearing chamber models as identifed by [8,12]. In parallel research an experimental test facility has been constructed that will allow visualisation and other data acquisition relating to oil shedding from an aeroengine ball bearing.…”

“…These so-called thin film models are based on lubrication theory with development for bearing chamber applications following chronolgically through Farrall et al [3], Williams [4], Kay et al [5] and Kakimpa et al [6]. Studies on more engine representative geometries, including [7][8][9] have investigated computationally the flow phenomenon inside the bearing chamber cavity. The recurring assumption in the models is that we understand the shedding characteristics of the oil from the bearing or in the simpler models, that the flow is a simple rimming flow.…”