An Analysis of Gas-Lubricated, Multileaf Foil Journal Bearings With Backing Springs

Heshmat, Crystal A.; Heshmat, Hooshang

doi:10.1115/1.2831272

Cited by 44 publications

(26 citation statements)

References 12 publications

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“…To address the engine system development issues that will make these machines a reality with high performance, reliability and long term storability, the authors have led the development and demonstrated the needed supporting foil bearing technologies ranging from improved damping and load capacity to high temperature, long life and low friction coatings for compliant foil bearings [3][4][5][6][7][8][9][10]. These recent developments indicate that compliant foil air bearing (CFB) technology has the capability to be used as main rotor supports for a wide array of gas turbine engines, even engines up to and exceeding 5,000 pounds of thrust.…”

Section: Introductionmentioning

confidence: 99%

Small Gas Turbine Engine Operating With High-Temperature Foil Bearings

Heshmat

Tomaszewski

Walton

2006

Volume 5: Marine; Microturbines and Small Turbomachinery; Oil and Gas Applications; Structures and Dynamics, Parts a and B

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A 134 Newton thrust class, 120,000 rpm turbojet was redesigned to incorporate a high-temperature compliant foil bearing aft of the turbine rotor and a compliantly mounted ball bearing forward of the centrifugal compressor-cold section. Two rotor-bearing system configurations were evaluated, one for operation above the bending critical speed and one for rigid rotor operation. Required characteristics for the foil bearing and ball bearing equipped with compliant foil damper mount were determined through a series of design tradeoff studies evaluating critical speeds and system stability. Following the design studies, the necessary hardware was fabricated, the engine assembled and operation to full speed achieved. Engine speed, rotor vibrations, compressor discharge pressure, exhaust gas temperature, thrust and fuel consumption were all recorded for both a baseline fluid lubricated ball bearing supported engine and the new turbojet engine using the hybrid foil bearing support system. Issues related to high-speed operation above the bending critical speed are identified and recommendations offered.Engine test data show that approximately 10% less fuel is consumed by the hybrid foil bearing mount system than the baseline conventional design. It is also shown that the foil bearing life was longer than the ball bearing life even though the foil bearing operated in the exhaust gas stream at temperatures exceeding 800°C. The results of this program demonstrate the feasibility of developing a completely oil-free foil bearing gas turbine engine.

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Section: Introductionmentioning

confidence: 99%

Small Gas Turbine Engine Operating With High-Temperature Foil Bearings

Heshmat

Tomaszewski

Walton

2006

Volume 5: Marine; Microturbines and Small Turbomachinery; Oil and Gas Applications; Structures and Dynamics, Parts a and B

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“…Analyses of foil bearings without backing springs have been presented by Zorzi [18] and Arakere and Nelson [19]. Later versions have a supportive spring behind each leaf which significantly increases the load capacity [1,20]. Furthermore, other new features could be found in some patents [21][22][23].…”

Section: Introductionmentioning

confidence: 98%

Structural Stiffness and Damping Coefficients of a Multileaf Foil Bearing With Bump Foils Underneath

Tian¹,

Sun

2013

Journal of Engineering for Gas Turbines and Power

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This paper presents a multileaf foil bearing (MLFB), which consists of four resilient top foils and four stiff bump foi I s underneath; thus, a high supporting capacity and a high damping capacity can be achieved. A specially designed test rig is used to identify the structural stiffness and damping coefficients of the MLFB. The rotor of the test rig is supported by two journal MLFBs and a thrust active magnetic bearing (AMB) and the static and dynamic loads are applied by two radial AMBs. The tests on MLFBs were conducted under conditions of no shaft rotation at different angular positions and journal displacements with different excitation frequency. A frequency domain identiflcation method is presented to determine the stiffness and damping coefficients. Static measurements show nonlinear deflections with applied forces, whichvaries with the orientation of the load angular position. The dynamic measurements show that the stijfness and equivalent viscous damping change with the excitation frequency. Furthermore, the stiffness and damping coefficients are related to the operating position where dynamic load tests were conducted. The investigation provides extensive measurements of the static and dynamic characteristics of the MLFB. These results can serve as a benchmark for the calibration of analytical tools under development.

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“…Heshmat et al (27,28) conducted a theoretical study about a novel multileaf foil bearing with backing supports from the patent structure by Silver and Wenban (29). Due to the introduction of compliance coefficient, the convergence of the EHD solution was improved, and the design guidelines were discussed.…”

Section: Introductionmentioning

confidence: 99%

The Effect of Area Contact on the Static Performance of Multileaf Foil Bearings

Zhu

et al. 2015

Tribology Transactions

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For multileaf foil bearings，the interactions between adjacent foils, foils and gas film are key to predict the bearing performance. However, most of the analytical models were based on line contact rather than area contact between adjacent foils and the latter may occur and play an important role in load capacity. In this study, the curved beam model is adopted to build up the elastohydrodynamic model considering the area contact between adjacent foils, which is solved iteratively coupling the Reynolds equation by the finite element method. An algorithm is developed to judge and determine the contact condition of adjacent foils. The simulation results show that the area contact between adjacent foils does occur and the contact area expands with the increasing of eccentricity ratios and rotational speeds, which make the film thickness distribution smooth and are beneficial to the increase of load capacity. The area contact occurs near the trailing end of the foils first, and then gradually expands. The later formed contact area bears greater load capacity instead of the early formed contact area, and the load capacity is mainly provided by the gas film on the foils with more area contact.

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An Analysis of Gas-Lubricated, Multileaf Foil Journal Bearings With Backing Springs

Cited by 44 publications

References 12 publications

Small Gas Turbine Engine Operating With High-Temperature Foil Bearings

Small Gas Turbine Engine Operating With High-Temperature Foil Bearings

Structural Stiffness and Damping Coefficients of a Multileaf Foil Bearing With Bump Foils Underneath

The Effect of Area Contact on the Static Performance of Multileaf Foil Bearings

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