Oil Droplet Impact Dynamics In Aero Engine Bearing Chambers Correlations Derived From Direct Numerical Simulations PDF Download

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Oil Droplet Impact Dynamics in Aero-Engine Bearing Chambers-Correlations derived from Direct Numerical Simulations

Oil Droplet Impact Dynamics in Aero-Engine Bearing Chambers-Correlations derived from Direct Numerical Simulations
Author: Davide Peduto
Publisher: Logos Verlag Berlin GmbH
Total Pages: 207
Release: 2015-06-30
Genre:
ISBN: 3832540016

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Bearing Chambers in Aero-Engines are located near the rolling-element type of bearings which support the shafts and accomodate the resulting thrust loads. One of the main task of the bearing chambers is, beside an efficient scavenging of the lubricating oil, the cooling of the hot compartments. A very complex two-phase air-oil flow takes usually place in these bearing chambers consisting of oil droplet-laden air flows and shear-driven liquid wall films. The interaction of the droplets with the wall films is significantly influencing the wall heat transfer and the cooling performance of these systems. For this reason, a detailed characterization and modelling of the mass and momentum exchange between droplets and wall films for the unique impingement parameter range in bearing chambers is inevitable. This scientific report investigates the oil droplet impact dynamics for typical impingement regimes relevant to aero-engine bearing chambers. The application of a Direct Numerical Simulation (DNS) technique based on the Volume-of-Fluid (VOF) method and coupled with a gradient-based adaptive mesh refinement (AMR) technique allowed to characterize the drop impact dynamics during various single micro- and millimeter drop impacts onto thin and thick films. With the help of a special numerical treatment, a self-perturbing mechanism is installed that leads to the correct resolution of the crown disintegration process. The numerical methodology was thoroughly validated using the experimental results of millimeter sized drop impacts onto deep liquid pools. These results were developed with an enhanced back-illuminated high-speed imaging and Particle Tracking Velocimetry (PTV) technique. New insights into the cavity penetration, the crown's breakup dynamics and the secondary droplet characteristics following a single drop impact have been developed with the help of the isolated variation of different parameters of influence. Particularly the influence of the Froude number, the impingement angle, and the cavity-wall interaction delivered results to date not reported in scientific literature. Beside the advances in fundamental physics describing the drop impact dynamics with the help of the numerical and experimental results, a set of correlations could also be derived. From these correlations, a drop-film interaction model was formulated that is suitable for the parameter range found in bearing chambers.


Oil Film Dynamics in Aero Engine Bearing Chambers

Oil Film Dynamics in Aero Engine Bearing Chambers
Author: Amir Aleem Hashmi
Publisher: Logos Verlag Berlin GmbH
Total Pages: 162
Release: 2012
Genre: Science
ISBN: 3832532285

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Aero engine bearing chambers are complex machine elements inside the engines, supporting up to three concentric shafts on bearings. For safety reasons, the aero engines always employ rolling-element type bearings and therefore require a sufficient oil supply for lubrication in order to guarantee a reliable operation. As a consequence, a complex two-phase flow consisting of oil and sealing air governs the bearing chambers. A highly dynamic oil film, flowing along the chamber walls, plays a vital role to fulfill the tasks of cooling, lubricating and cleaning the bearing chambers. The design and optimization process of the bearing chambers requires a detailed understanding in order to accurately simulate the film behaviour inside the bearing chambers. Based on the earlier experimental investigations, it is known that near the scavenge off-take a relatively thick film exists. The numerical model to simulate these films must therefore take into account the elliptical behaviour of such films. Among the different models, the Volume Of Fluid (VOF) Model offers the best compromise between accuracy and efforts. However, preliminary attempts to model a fully developed and turbulent test case from literature revealed an unphysical pressure drop and velocity profile in the gas phase above the film flow. An inadequate turbulence modelling near the gas-liquid interface was identified as the problem source. The 2-Equation turbulence models (k- epsilon & k- omega) were extended to achieve a substantial improvement.


Oil Film Dynamics in Aero Engine Bearing Chambers

Oil Film Dynamics in Aero Engine Bearing Chambers
Author: Amir A. Hashmi
Publisher:
Total Pages: 164
Release: 2012
Genre: Electronic book
ISBN: 9783832593650

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Annotation Aero engine bearing chambers are complex machine elements inside the engines, supporting up to three concentric shafts on bearings. For safety reasons, the aero engines always employ rolling-element type bearings and therefore require a sufficient oil supply for lubrication in order to guarantee a reliable operation. As a consequence, a complex two-phase flow consisting of oil and sealing air governs the bearing chambers. A highly dynamic oil film, flowing along the chamber walls, plays a vital role to fulfill the tasks of cooling, lubricating and cleaning the bearing chambers. The design and optimization process of the bearing chambers requires a detailed understanding in order to accurately simulate the film behaviour inside the bearing chambers. Based on the earlier experimental investigations, it is known that near the scavenge off-take a relatively thick film exists. The numerical model to simulate these films must therefore take into account the elliptical behaviour of such films. Among the different models, the Volume Of Fluid (VOF) Model offers the best compromise between accuracy and efforts. However, preliminary attempts to model a fully developed and turbulent test case from literature revealed an unphysical pressure drop and velocity profile in the gas phase above the film flow. An inadequate turbulence modelling near the gas-liquid interface was identified as the problem source. The 2-Equation turbulence models (k- epsilon & k- omega) were extended to achieve a substantial improvement.


Bulletin of the Atomic Scientists

Bulletin of the Atomic Scientists
Author:
Publisher:
Total Pages: 104
Release: 1970-12
Genre:
ISBN:

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The Bulletin of the Atomic Scientists is the premier public resource on scientific and technological developments that impact global security. Founded by Manhattan Project Scientists, the Bulletin's iconic "Doomsday Clock" stimulates solutions for a safer world.


Technical Literature Abstracts

Technical Literature Abstracts
Author: Society of Automotive Engineers
Publisher:
Total Pages: 520
Release: 1995
Genre: Technical literature
ISBN:

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Flow and Heat Transfer in Rotating-disc Systems

Flow and Heat Transfer in Rotating-disc Systems
Author: John Michael Owen
Publisher:
Total Pages: 312
Release: 1989
Genre: Science
ISBN: 9780863800900

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Discussing fluid mechanics and heat transfer in rotating-disc systems, this text simplifies and extends existing information to provide a basic understanding of the subject. Physical insight, mathematical models and experimental data are used to explain the flow structure and provide theoretical methods and correlations which will be of use to research workers and designers.


Unsteady Computational Fluid Dynamics in Aeronautics

Unsteady Computational Fluid Dynamics in Aeronautics
Author: P.G. Tucker
Publisher: Springer Science & Business Media
Total Pages: 432
Release: 2013-08-30
Genre: Technology & Engineering
ISBN: 9400770499

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The field of Large Eddy Simulation (LES) and hybrids is a vibrant research area. This book runs through all the potential unsteady modelling fidelity ranges, from low-order to LES. The latter is probably the highest fidelity for practical aerospace systems modelling. Cutting edge new frontiers are defined. One example of a pressing environmental concern is noise. For the accurate prediction of this, unsteady modelling is needed. Hence computational aeroacoustics is explored. It is also emerging that there is a critical need for coupled simulations. Hence, this area is also considered and the tensions of utilizing such simulations with the already expensive LES. This work has relevance to the general field of CFD and LES and to a wide variety of non-aerospace aerodynamic systems (e.g. cars, submarines, ships, electronics, buildings). Topics treated include unsteady flow techniques; LES and hybrids; general numerical methods; computational aeroacoustics; computational aeroelasticity; coupled simulations and turbulence and its modelling (LES, RANS, transition, VLES, URANS). The volume concludes by pointing forward to future horizons and in particular the industrial use of LES. The writing style is accessible and useful to both academics and industrial practitioners. From the reviews: "Tucker's volume provides a very welcome, concise discussion of current capabilities for simulating and modellng unsteady aerodynamic flows. It covers the various pos sible numerical techniques in good, clear detail and presents a very wide range of practical applications; beautifully illustrated in many cases. This book thus provides a valuable text for practicing engineers, a rich source of background information for students and those new to this area of Research & Development, and an excellent state-of-the-art review for others. A great achievement." Mark Savill FHEA, FRAeS, C.Eng, Professor of Computational Aerodynamics Design & Head of Power & Propulsion Sciences, Department of Power & Propulsion, School of Engineering, Cranfield University, Bedfordshire, U.K. "This is a very useful book with a wide coverage of many aspects in unsteady aerodynamics method development and applications for internal and external flows." L. He, Rolls-Royce/RAEng Chair of Computational Aerothermal Engineering, Oxford University, U.K. "This comprehensive book ranges from classical concepts in both numerical methods and turbulence modelling approaches for the beginner to latest state-of-the-art for the advanced practitioner and constitutes an extremely valuable contribution to the specific Computational Fluid Dynamics literature in Aeronautics. Student and expert alike will benefit greatly by reading it from cover to cover." Sébastien Deck, Onera, Meudon, France


The Engineering Index Annual

The Engineering Index Annual
Author:
Publisher:
Total Pages: 2282
Release: 1988
Genre: Engineering
ISBN:

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Since its creation in 1884, Engineering Index has covered virtually every major engineering innovation from around the world. It serves as the historical record of virtually every major engineering innovation of the 20th century. Recent content is a vital resource for current awareness, new production information, technological forecasting and competitive intelligence. The world?s most comprehensive interdisciplinary engineering database, Engineering Index contains over 10.7 million records. Each year, over 500,000 new abstracts are added from over 5,000 scholarly journals, trade magazines, and conference proceedings. Coverage spans over 175 engineering disciplines from over 80 countries. Updated weekly.


The Use of Dispersants in Marine Oil Spill Response

The Use of Dispersants in Marine Oil Spill Response
Author: National Academies of Sciences, Engineering, and Medicine
Publisher: National Academies Press
Total Pages: 341
Release: 2020-04-24
Genre: Nature
ISBN: 0309478219

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Whether the result of an oil well blowout, vessel collision or grounding, leaking pipeline, or other incident at sea, each marine oil spill will present unique circumstances and challenges. The oil type and properties, location, time of year, duration of spill, water depth, environmental conditions, affected biomes, potential human community impact, and available resources may vary significantly. Also, each spill may be governed by policy guidelines, such as those set forth in the National Response Plan, Regional Response Plans, or Area Contingency Plans. To respond effectively to the specific conditions presented during an oil spill, spill responders have used a variety of response optionsâ€"including mechanical recovery of oil using skimmers and booms, in situ burning of oil, monitored natural attenuation of oil, and dispersion of oil by chemical dispersants. Because each response method has advantages and disadvantages, it is important to understand specific scenarios where a net benefit may be achieved by using a particular tool or combination of tools. This report builds on two previous National Research Council reports on dispersant use to provide a current understanding of the state of science and to inform future marine oil spill response operations. The response to the 2010 Deepwater Horizon spill included an unprecedented use of dispersants via both surface application and subsea injection. The magnitude of the spill stimulated interest and funding for research on oil spill response, and dispersant use in particular. This study assesses the effects and efficacy of dispersants as an oil spill response tool and evaluates trade-offs associated with dispersant use.