Load Capacity Estimation of Foil Air Journal Bearings for Oil-Free Turbomachinery Applications

DellaCorte, Christopher; Valco, Mark J.

doi:10.1080/10402000008982410

Cited by 229 publications

(110 citation statements)

References 8 publications

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“…However, it may be possible that, due to the bearing's axial length, the fluid's rotational inertia and a design feature incorporated into the bearing to minimize side leakage (ref. 10), the magnitude of the pressure gradient is insufficient to force all the air out of the bearing. Left in the middle of the bearing is a slug of fluid trapped in the circumferential flow.…”

Section: Discussion Of Resultsmentioning

confidence: 99%

An Experimental Investigation into the Temperature Profile of a Compliant Foil Air Bearing

Radil

Zeszotek

2004

Tribology Transactions

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Public reporting burden for this collection of Information is estimated to average 1 liour per response, including tlie time for reviewing instructions, searcfiing existing data sources, gatfiering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden, to Washington Headquarters Services, Directorate for Information Operations and Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302, and to the Office of Management and Budget, Paperwork Reduction Project (0704-0188), Washington, DC 20503. AGENCY USE ONLY (/.eai'e WanA)REPORT DATE May 2004 REPORT TYPE AND DATES COVERED Technical Memorandum TITLE AND SUBTITLE 12b. DISTRIBUTION CODE ABSTRACT (Maximum 200 words)A series of tests was performed to determine the internal temperature profile in a compliant bump-type foil journal air bearing operating at room temperature under various speeds and load conditions. The temperature profile was collected by instrumenting a foil bearing with nine, type K thermocouples arranged in the center and along the bearing's edges in order to measure local temperatures and estimate thermal gradients in the axial and circumferential directions. To facilitate the measurement of maximum temperatures from viscous shearing in the air film, the thermocouples were tack welded to the backside of the bumps that were in direct contact with the top foil. The mating journal was coated with a high temperature solid lubricant that, together with the bearing, underwent high temperature start-stop cycles to produce a smooth, steady-state run-in surface. Tests were conducted at speeds from 20 to 50 krpm and loads ranging from 9 to 222 N. The results indicate that, over the conditions tested, both journal rotational speed and radial load are responsible for heat generation with speed playing a more significant role in the magnitude of the temperatures. The temperatiire distribution was nearly symmetric about the bearing center at 20 and 30 krpm but became slightiy skewed toward one side at 40 and 50 krpm. Surprisingly, the maximum temperatores did not occur at the bearing edge where the minimum film thickness is expected but rather in the middle of the bearing where analytical investigations have predicted the air film to be much thicker. Thermal gradients were common during testing and were strongest in the axial direction from the middle of the bearing to its edges, reaching 3.78 °C/mm. The temperature profile indicated the circumferential thermal gradients were negligible. SUBJECT TERMSFoil air bearings; Gas bearings; Turbomachinery • TECHNICAL PUBLICATION. Reports of completed research or a major significant phase of research that present the results of NASA programs and include extensive data or theoretical analysis. Includes compilations of significant scientific and technical data and information deemed to be of continuing reference value. NA...

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Section: Discussion Of Resultsmentioning

confidence: 99%

An Experimental Investigation into the Temperature Profile of a Compliant Foil Air Bearing

Radil

Zeszotek

2004

Tribology Transactions

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“…San Andrés et al [29] who compared predicted unbalance response and critical speeds to experimental results. Dellacorte and Valco [30] experimentally investigated the load carrying capacity of foil bearings and derived a rule of thumb, and Howard [31] investigated the effect of misalignment on the bearing performance. However, the number of authors dealing with the experimental identification of the linearised dynamic stiffness and damping coefficients is limited.…”

Section: Introductionmentioning

confidence: 99%

Experimental and theoretical analysis of a rigid rotor supported by air foil bearings

Larsen

Hansen

Santos

2014

Mechanics & Industry

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-The popularity of compressors utilizing foil bearings is increasing. Their mechanical design is challenging, and an accurate prediction of the bearing coefficients is important. A mathematical model taking into account the foil structure, and the detailed geometry of a three pad foil bearing are presented. The steady state solution and dynamic coefficients are obtained through zeroth and first order perturbed equations respectively. Analysis of the foil structure reveals the importance of distinguishing between a static foil stiffness for the zeroth order equation and a dynamic stiffness for the first order equation. Calculated bearing coefficients are compared to experimental results obtained from a dedicated test rig. Generally, good agreement is observed and minor discrepancies for the damping coefficients are discussed.

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“…Coupling fluid dynamics with structural mechanics has made modeling of foil gas bearings and rotors that rely upon them very challenging and uncertain (Ref. 7). In the past, the development of new machines has often been based on previously fielded machines or relied heavily on hardware intensive make-and-break trial and error approaches (Ref.…”

Section: Introductionmentioning

confidence: 99%

“…Presently, however, only a method to estimate foil bearing load capacity exists (Ref. 7). This load capacity estimation technique was developed by examining experimentally measured load capacity data from numerous foil bearing tests to develop a simple linear algebraic relationship between bearing size, design complexity and operating speed and the resulting load capacity.…”

Section: Introductionmentioning

confidence: 99%

Stiffness and Damping Coefficient Estimation of Compliant Surface Gas Bearings for Oil-Free Turbomachinery

DellaCorte

2011

Tribology Transactions

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Foil gas bearings are a key technology in many commercial and emerging Oil-Free turbomachinery systems. These bearings are non-linear and have been difficult to analytically model in terms of performance characteristics such as load capacity, power loss, stiffness and damping. Previous investigations led to an empirically derived method, a rule-ofthumb, to estimate load capacity. This method has been a valuable tool in system development. The current paper extends this tool concept to include rules for stiffness and damping coefficient estimation. It is expected that these rules will further accelerate the development and deployment of advanced Oil-Free machines operating on foil gas bearings.

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Load Capacity Estimation of Foil Air Journal Bearings for Oil-Free Turbomachinery Applications

Cited by 229 publications

References 8 publications

An Experimental Investigation into the Temperature Profile of a Compliant Foil Air Bearing

An Experimental Investigation into the Temperature Profile of a Compliant Foil Air Bearing

Experimental and theoretical analysis of a rigid rotor supported by air foil bearings

Stiffness and Damping Coefficient Estimation of Compliant Surface Gas Bearings for Oil-Free Turbomachinery

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