Influence of High Rotational Speeds on Heat Transfer and Oil Film Thickness in Aero-Engine Bearing Chambers

Wittig, Sigmar; Glahn, Axel; Himmelsbach, Johann

doi:10.1115/1.2906833

Cited by 52 publications

(36 citation statements)

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“…Wittig et al [15] developed and built a test facility which allowed for the first time a detailed investigation into oil/air flow phenomena and related heat transfer processes in bearing chamber. On the test facility, Glahn et al [1] carried out experimental investigation on size and velocity of droplet which was atomized by bearing.…”

Section: Introductionmentioning

confidence: 99%

Ligament and Droplet Generation by Oil Film on a Rotating Disk

Sun

Chen

Wang

et al. 2015

International Journal of Aerospace Engineering

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The lubrication and heat transfer designs of bearing chamber depend on an understanding of oil/air two-phase flow. As initial and boundary conditions, the characteristics of ligament and droplet generation by oil film on rotating parts have significant influence on the feasibility of oil/air two-phase flow analysis. An integrated model to predict the oil film flow, ligament number, and droplet Sauter mean diameter (SMD) of a rotating disk, which is an abstraction of the droplet generation sources in a bearing chamber, is developed based on the oil film force balance analysis and wave theory. The oil film thickness and velocity, ligaments number, and droplet SMD are calculated as functions of the rotating disk radius, rotational speed and oil volume flow rate and oil properties. The theoretical results show that the oil film thickness and SMD are decreased with an increasing rotational speed, while the radial, transverse velocities, and ligament number are increased. The oil film thickness, radial velocity, and SMD are increased with an increasing oil flow rate, but the transverse velocity and ligament number are decreased. A test facility is built for the investigation into the ligament number of a rotating disk, and the measurement of ligament number is carried out by means of a high speed photography.

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Section: Introductionmentioning

confidence: 99%

Ligament and Droplet Generation by Oil Film on a Rotating Disk

Sun

Chen

Wang

et al. 2015

International Journal of Aerospace Engineering

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“…Wittig et al [8,9] reported an experimental investigation into oil film thickness and heat transfer in aero-engine bearing chambers under the influence of high rotational speeds up to 16000 rpm. In following work [10,11] measurements of oil film velocity profiles in a high speed bearing chamber rig simulating engine conditions were carried out and the results were compared with theoretical predictions.…”

Section: Previous Workmentioning

confidence: 99%

“…A decision was made to model the oil as droplets as this allowed a Lagrangian approach to be used. A range of droplet diameters were investigated using diameters suggested by previous experimental studies [8][9][10][11]. Droplet release location and velocity were also not known exactly although clearly the region is identified by the location of the bearing.…”

Section: Simplifications and Assumptionsmentioning

confidence: 99%

Study of aero-engine oil-air separators

Eastwick

Simmons

Wang

et al. 2006

Proceedings of the Institution of Mechanical Engineers, Part A:

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For aero-engines, oil/air separation is a key function and one approach to assessing separator effectiveness is computational fluid dynamics (CFD). The two-phase flow is complex and oil can be present in different forms (for example droplets, mist, film).However, necessary modelling simplifications may affect solution accuracy and range of validity. This paper presents a modelling methodology for oil/air separators; the effect of simplifications is discussed and their relative magnitude assessed.Comparison with available experimental data is presented. It is concluded that whilst simplification has an impact, the significant features of the oil-air separator are predicted with sufficient accuracy to allow design comparisons.Two separator configurations, one internal to a bearing chamber and one external, are modelled and the data presented. Flow fields are compared and the effectiveness of the separators at removing oil droplets prior to impact on the breather (primary separation) presented. The separation performance of the external design is largely independent of shaft speed with all droplets greater than 3µm removed before impact on the breather. The critical droplet diameter of the internal design is larger, varying -2 -with breather configuration and shaft speed but the power loss is an order of magnitude lower than for the external design.

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“…Of particular interest to the present study are the laminar shear-driven thin-film rimming flows inside aero-engine bearing chambers where thin liquid films are driven by an inter-facial shear stress in the presence of a gravitational field, surface tension and pressure gradient forces [2], [3,4]. The problem of a two-dimensional (2D) classical shear driven rimming flow, as shown in Figure 1, has been used to investigate the problem of thin-film flow, assess existing formulations and based on the findings propose a solution strategy.…”

Section: Introductionmentioning

confidence: 99%

The Depth-Averaged Numerical Simulation of Laminar Thin-Film Flows With Capillary Waves

Kakimpa

Morvan

Hibberd

2016

Journal of Engineering for Gas Turbines and Power

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Thin-film flows encountered in engineering systems such as aeroengine bearing chambers often exhibit capillary waves and occur within a moderate to high Weber number range. Although the depth-averaged simulation of these thin-film flows is computationally efficient relative to traditional VOF methods, numerical challenges remain particularly for solutions involving capillary waves and in the higher Weber number, low surface tension range. A depth-averaged approximation of the Navier-Stokes equations has been used to explore the effect of surface tension, grid resolution and inertia on thin-film rimming solution accuracy and numerical stability. In shock and pooling solutions where capillary ripples are present, solution stability and accuracy are shown to be highly sensitive to surface tension. The common practice in analytical studies of enforcing unphysical low Weber number stability constraints is shown to stabilise the solution by artificially damping capillary oscillations. This approach however although providing stable solutions is shown to adversely affect solution accuracy. An alternative grid resolution based stability criteria is demonstrated and used to obtain numerically stable shock and pooling solutions without recourse to unphysical surface tension values. This allows for the accurate simulation of thin-film flows with capillary waves within the constrained parameter space corresponding to physical material and flow properties. Results obtained using the proposed formulation and solution strategy show good agreement with available experimental data from

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Influence of High Rotational Speeds on Heat Transfer and Oil Film Thickness in Aero-Engine Bearing Chambers

Cited by 52 publications

References 0 publications

Ligament and Droplet Generation by Oil Film on a Rotating Disk

Ligament and Droplet Generation by Oil Film on a Rotating Disk

Study of aero-engine oil-air separators

The Depth-Averaged Numerical Simulation of Laminar Thin-Film Flows With Capillary Waves

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