Effect of Axial Oscillation on Performance of Hydrodynamic Journal Bearings PDF Download
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Author: Thomas Wirsing
Publisher:
ISBN:
Category : Bearings (Machinery)
Languages : en
Pages : 137
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Book Description
The hydrodynamic coefficients of a journal bearing set with the bearing subjected to axial oscillation are determined in this work. The Navier-Stokes equations were used to account for the axial component of the relative motion between the journal and the bearing. Numerical solution of the Navier-Stokes equations yielded the pressure distribution within the cavity of the bearing. This pressure distribution was then integrated over the surface of the bearing to obtain the two orthogonal force components. The derivatives of these force components were then taken with respect to the displacement and velocity of the journal that are co-linear with these forces. This yielded the hydrodynamic coefficients. To conduct a parametric study, the bearing design parameters were chosen such that the Sommerfeld number was equal to one. The axial oscillation of the bearing was modeled as a purely sinusoidal motion, with an amplitude of one millimeter and a frequency range of 0-304 rads/s. This study shows that for a bearing axial frequency up to 304 rads/s the bearing dynamic coefficients exhibit an increase in their deviation from the values of a stationary bearing. This study further shows that at the frequency of 300 rads/s the stiffness and damping coefficients vary dramatically over the course of cycle for the bearing set described in this work. This study shows Kxy changes from 1.711073 to 5.235242 back to 1.711073 again to 5.235242 and then back to 1.711073 as the bearing completes one-half cycle of travel.
Author: Thomas Wirsing
Publisher:
ISBN:
Category : Bearings (Machinery)
Languages : en
Pages : 137
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Book Description
The hydrodynamic coefficients of a journal bearing set with the bearing subjected to axial oscillation are determined in this work. The Navier-Stokes equations were used to account for the axial component of the relative motion between the journal and the bearing. Numerical solution of the Navier-Stokes equations yielded the pressure distribution within the cavity of the bearing. This pressure distribution was then integrated over the surface of the bearing to obtain the two orthogonal force components. The derivatives of these force components were then taken with respect to the displacement and velocity of the journal that are co-linear with these forces. This yielded the hydrodynamic coefficients. To conduct a parametric study, the bearing design parameters were chosen such that the Sommerfeld number was equal to one. The axial oscillation of the bearing was modeled as a purely sinusoidal motion, with an amplitude of one millimeter and a frequency range of 0-304 rads/s. This study shows that for a bearing axial frequency up to 304 rads/s the bearing dynamic coefficients exhibit an increase in their deviation from the values of a stationary bearing. This study further shows that at the frequency of 300 rads/s the stiffness and damping coefficients vary dramatically over the course of cycle for the bearing set described in this work. This study shows Kxy changes from 1.711073 to 5.235242 back to 1.711073 again to 5.235242 and then back to 1.711073 as the bearing completes one-half cycle of travel.
Author: Bharat C. Kamdar
Publisher:
ISBN:
Category :
Languages : en
Pages : 178
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Book Description
Author: J. Frene
Publisher: Elsevier
ISBN: 0080534317
Category : Technology & Engineering
Languages : en
Pages : 499
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Book Description
Hydrodynamic Lubrication is the culmination of over 20 years close, collaborative work by the five authors and discusses the practical use of the formalization of low pressure lubrication. The work concentrates on the developments to journal and thrust bearings and includes subjects such as: • the dynamic behaviour of plain and tilting-pads • the thermal aspects • the positive and negative effects of non-cyclindricity and shape defects resulting from manufacturing or operation • the effects of inertia • the appearance of Taylor's vortices and of turbulence and their repercussions. The book contains an abundance of test results objectively compared with theoretical conclusions and a chapter on "technical considerations" to ensure that draft mechanisms will work satisfactorily under the imposed conditions. Hydrodynamic Lubrication is an essential reference book for future and practising engineers who want to put hydrodynamic and hydrostatic journal bearings and thrust bearings into operation under conditions of total safety.
Author: Hazem Ezzat Ahmed Ezzat
Publisher:
ISBN:
Category :
Languages : en
Pages : 632
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Book Description
Author: Francis Harvey Raven
Publisher:
ISBN:
Category : Hydrodynamics
Languages : en
Pages : 62
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Book Description
Author: Kevin Amith Mathias
Publisher: LAP Lambert Academic Publishing
ISBN: 9783659341403
Category :
Languages : en
Pages : 84
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Book Description
This book mainly focuses on the understanding of basic concepts related Hydrodynamic Lubrication. In this more emphasis is given on steadily loaded oil film Journal Bearings. It includes discussion on derivation of generalised Reynold's equation for specific cases of Journal Bearing. In case of steadily loaded Journal Bearings viscosity is assumed to constant. But in reality because of rise in temperature, viscosity of oil film changes. In this book effect of variation of viscosity on the performance of Journal bearing is discussed. Plots of steady state, dynamic and thermo-hydrodynamic analysis are included in this book.
Author: Troy Snyder
Publisher:
ISBN:
Category : Bearings (Machinery)
Languages : en
Pages : 0
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Book Description
The compliant marine bearing is a type of journal bearing which features an elastomeric bushing and commonly utilizes water as the bearing lubricant. The term compliant follows from the deformation of the elastomeric bushing at substantially reduced hydrodynamic pressures compared to bearings with bushings comprised of metals such as bronze, brass, or steel. The operating regime of marine bearings under purely hydrdocynamic action is aptly called soft-EHL in which elasto-hydrodynamic lubrication occurs at sub-Hertizan pressures within the bearings' conformal contacts. Marine bearing bushings are typically profiled designs with lubricant grooves distributed around their circumference. The lubricant grooves serve as axial flow passages and contribute negligibly to the generation of hydrodynamic bearing pressures. The regions between the lubricant grooves are referred to as lands and generate hydrodynamic bearing forces which support static an dynamic radial loads applied to the bearings. Compliant marine bearings primarily serve in marine applications as stern tube and strut bearings, which support the propeller driveshaft at the rear of shipping vessels. This work provides a detailed theoretical development of a Reynolds equation-based model suitable to predict the static and dynamic performance of hydrodynamic bearings with compliant bushings. The dynamic performance is embodied in linearized dynamic coefficients which are calculated from a perturbed set of differential equations. The numerical solution of the model is exercised through a wide number of application cases to verify several modeling assumptions related to: bushing compliance, fluidinertia, and turbulence. Primarily, a simplified slider bearing geometry is investigated as it functions as a surrogate for a single stave in a full marine bearing. A FRF-based method to predict the dynamic behavior of hydrodynamic bearings (and seals) within a higher-fidelity CFD environment has been developed and deployed by leveraging the open-source continuum mechanics library OpenFOAM. The method is successfully employed in the evaluation of the dynamic coefficients of rigid slider and journal bearing geometries. The dynamic coefficients predicted by the FRF-based approachand the perturbed Reynolds equation showed good coincidence for the linear slider and journal bearing geometries and operating conditions considered. The FRF-based approach for the identification of bearing dynamic coefficients is general and applicable to bearings which feature compliant bushings or complex geometric features. Numerical results from models of varying complexity are compared with each other in an effort to verify the assumptions associated with the compliant, perturbed Reynolds equation. Modeling assumptions regarding lubricant inertia, turbulence, and the constitutive modeling of the bearing bushing are explored in detail.
Author: Hazem Ahmed Mahmoud Ezzat
Publisher:
ISBN:
Category : Fluid-film bearings
Languages : en
Pages : 246
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Book Description
Author: Nadia Bendaoud
Publisher: Cambridge Scholars Publishing
ISBN: 1527592413
Category : Technology & Engineering
Languages : en
Pages : 318
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Book Description
Hydrodynamic bearings and aerodynamic bearings are components which ensure the guiding of rotating machines, such as turbines and reactors. This equipment operates under very severe operating conditions, with a high rotational speed and high radial load. In order to improve the hydrodynamic performance of these rotating machines, manufacturers specializing in the manufacture of hydrodynamic plain bearings have designed a bearing model with its textured interior surface. This book provides a numerical analysis carried out to observe the effect of a turbulent fluid flow in a non-textured and textured plain bearing and to see the improvement in hydrodynamic and tribological performance on both un-textured and textured surfaces of plain bearings, under severe operating parameters. It also presents an analysis of the structural behavior of a hydrodynamic and aerodynamic bearing with a non-textured and textured surface.
Author: J. K. Wang
Publisher: John Wiley & Sons
ISBN: 1118536347
Category : Science
Languages : en
Pages : 216
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Book Description
Thermohydrodynamic Instability in Fluid-Film Bearings aims to establish instability criteria for a rotor-bearing system associated with fluid-film journal bearings. • It focuses on how the influencing factors such as rotor flexibility, manufacturing imperfections such as residual shaft unbalance, and service-related imperfections such as uneven wear affect the stability of a rotor-bearing system • It shows how the specific operating conditions such as oil inlet temperature, inlet pressure, and inlet position of a rotor-bearing system directly influence the system stability • General design guidelines have been summarized to guide the engineering system design and the correction of failure and/or malfunction
