Investigation of Foil Bearings with Particular Emphasis on Gas Lubricated Films PDF Download
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Author: A. Eshel
Publisher:
ISBN:
Category :
Languages : en
Pages : 16
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Book Description
The report outlines foil bearing research which has been carried out. It also lists the publications which have originated from the research. (Author).
Author: A. Eshel
Publisher:
ISBN:
Category :
Languages : en
Pages : 16
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Book Description
The report outlines foil bearing research which has been carried out. It also lists the publications which have originated from the research. (Author).
Author: Ampex Corporation. Advanced Technology Division
Publisher:
ISBN:
Category : Fluid-film bearings
Languages : en
Pages : 16
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Book Description
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 30
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Book Description
Foil air bearing load capacity tests were conducted to investigate if a solid lubricant coating applied to the surface of the bearing's top foil can function as a break-in coating. Two foil coating materials, a conventional soft polymer film (polyimide) and a hard ceramic (alumina), were independently evaluated against as-ground and worn (run-in) journals coated with NASA PS304, a high-temperature solid lubricant composite coating. The foil coatings were evaluated at journal rotational speeds of 30000 rpm and at 25 deg C. Tests were also performed on a foil bearing with a bare (uncoated) nickel-based superalloy top foil to establish a baseline for comparison. The test results indicate that the presence of a top foil solid lubricant coating is effective at increasing the load capacity performance of the foil bearing. Compared to the uncoated baseline, the addition of the soft polymer coating on the top foil increased the bearing load coefficient by 120 percent when operating against an as-ground journal surface and 85 percent against a run-in journal surface. The alumina coating increased the load coefficient by 40 percent against the as-ground journal but did not have any affect when the bearing was operated with the run-in journal. The results suggest that the addition of solid lubricant films provide added lubrication when the air film is marginal indicating that as the load capacity is approached foil air bearings transition from hydrodynamic to mixed and boundary lubrication.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 180
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Book Description
Author:
Publisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 652
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Book Description
Author: United States. Congress. House. Committee on Science and Technology. Subcommittee on Energy Development and Applications
Publisher:
ISBN:
Category : Energy policy
Languages : en
Pages : 486
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Book Description
Author: Mathieu Garcia
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
Internal experiments at Liebherr-Aerospace FRANCE on new refrigerant-lubricated compressor designs have shown that under specific operating conditions, a mixture of vapor and liquid appears in the compressor, instead of a single-phase vapor flow. Therefore, refrigerant-lubricated foil bearings behavior is studied, including the likelihood of two-phase flow in the lubricant. We focus on the lubricant behavior only, in the operating conditions of foil bearings. The Thermo-Hydrodynamic approach describes lubricant characteristics such as pressure, density, viscosity, and temperature. It involves the use of a generalized Reynolds equation for turbulent flow, a nonlinear cubic equation of state for two-phase flow and a 3D turbulent thin-film energy equation. Journal bearing global parameters are calculated for steady-state conditions.
Author: Leister, Tim
Publisher: KIT Scientific Publishing
ISBN: 3731511126
Category : Technology & Engineering
Languages : en
Pages : 192
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Book Description
The gas foil bearing (GFB) technology is a key factor for the transition to oil-free rotating machinery. Among numerous advantages, GFBs offer the unique ability to be lubricated with working fluids such as refrigerants. However, the computational analysis of refrigerant-lubricated GFB–rotor systems represents an interdisciplinary problem of enormous complexity. This work pushes forward existing limits of feasibility and establishes a new strategy that enables stability and bifurcation analyses.
Author: C. DellaCorte
Publisher:
ISBN:
Category : Nickel alloys
Languages : en
Pages : 22
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Book Description
The performance and durability of advanced, high temperature foil air bearings are evaluated under a wide range (10-50 kPa) of loads at temperatures from 25 to 650 deg C. The bearings are made from uncoated nickel based superalloy foils. The foil surface experiences sliding contact with the shaft during initial start/stop operation. To reduce friction and wear, the solid lubricant coating, PS 304, is applied to the shaft by plasma spraying. PS304 is a NiCr based Cr2O3 coating with silver and barium fluoride/calcium fluoride solid lubricant additions. The results show that the bearings provide lives well in excess of 30,000 cycles under all of the conditions tested. Several bearings exhibited lives in excess of 100,000 cycles. Wear is a linear function of the bearing load. The excellent performance measured in this study suggests that these bearings and the PS 304 coating are well suited for advanced high temperature, oil-free turbomachinery applications.
Author: A. Eshel
Publisher:
ISBN:
Category :
Languages : en
Pages : 23
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Book Description
The effect of external pressure exerted on foil bearings is studied. Analysis and numerical results are provided for its influence on the bearing gap. It is shown that a substantial reduction in film thickness can be achieved by applying small pressures in the inlet zone. The effect of several pertinent parameters is presented and discussed. (Author).
