This study aims to tailor the bearing stiffness for enhancing the load-carrying capacity of foil thrust bearings. New architectures for the bump foil are introduced with structural stiffness tailored in the radial and circumferential directions to ensure a converging gas film under high axial loads while maintaining a reasonable bearing compliance to accommodate thermal as well as mechanical distortions. The structural stiffness of the bearing is calculated with an analytical method previously introduced by the authors, and the flow in the gas film is modeled with 2-D compressible Reynolds equation. The Couette Approximation technique is used to calculate the temperature distribution in the gas film and the small perturbations method is used to calculate its dynamic force coefficients. Enhanced load capacity could be obtained with the introduced bump foil designs.
Agrawal GL. Foil air/gas bearing technology – an overview. In: International gas turbine & aeroengine Congress & exhibition, Orlando, Florida, USA; June 2–5, 1997, ASME Paper No. 97-GT-347.
4.
DellacorteCValcoMJ. Load capacity estimation of foil air journal bearings for oil-free turbomachinery applications. Tribol Trans2000; 43: 795–801.
5.
DellaCorteCRadilKCBrucknerRJ. Design, fabrication, and performance of open source generation I and II compliant hydrodynamic gas foil bearings. Tribol Trans2008; 51: 254–264.
6.
DellaCorteCBrucknerRJ. Remaining technical challenges and future plans for oil-free turbomachinery. J Eng Gas Turbine Power2011; 133: 042502–042502.
7.
Heshmat H. Stepped, split, cantilevered compliant bearing support. Patent 4,277,112, USA, 1981.
8.
Gray S and Heshmat H. Support element for compliant hydrodynamic thrust bearing. Patent 4,277,111, USA, 1981.
9.
Gu A and Nadjafi R. Foil thrust bearing with varying radial and circumferential stiffness. Patent 5,248,205, USA, 1993.
10.
Heshmat H. High load capacity compliant foil hydrodynamic thrust bearing. Patent 5,833,369, USA, 1997.
11.
IordanoffI. Analysis of an aerodynamic compliant foil thrust bearing: method for a rapid design. J Tribol1999; 121: 816–822.
12.
HeshmatCAXuDSHeshmatH. Analysis of gas lubricated foil thrust bearings using coupled finite element and finite difference methods. J Tribol2000; 122: 199–204.
13.
ParkDJKimCHJangGH. Theoretical considerations of static and dynamic characteristics of air foil thrust bearing with tilt and slip flow. Tribol Int2008; 41: 282–295.
14.
Bruckner RJ. Simulation and modeling of the hydrodynamic, thermal, and structural behavior of foil thrust bearings. PhD Thesis, Case Western Reserve University, USA, 2004.
15.
LeeDHKimDJ. Design and performance prediction of hybrid air foil thrust bearings. J Eng Gas Turbines Power2011; 133: 042501–042501.
16.
LeeDHKimDJ. Three-dimensional thermohydrodynamic analyses of Rayleigh step air foil thrust bearing with radially arranged bump foils. Tribol Trans2011; 54: 432–448.
17.
ConboyTM. Real-gas effects in foil thrust bearings operating in the turbulent regime. J Tribol2013; 135: 031703–031703.
18.
GadAMKanekoS. A new structural stiffness model for bump-type foil bearings: application to generation II gas lubricated foil thrust bearing. J Tribol2014; 136: 041701–041701.
19.
GadAMKanekoS. Performance characteristics of gas-lubricated bump-type foil thrust bearing. Proc IMechE, Part J: J Engineering Tribology2014; 229: 746–762.
20.
Dykas BD. Factors influencing the performance of foil gas thrust bearings for oil-free turbomachinery applications. PhD Thesis, Case Western Reserve University, USA, 2006.
21.
Dickman JR. An investigation of gas foil thrust bearing performance and its influencing factors. MSc Thesis, Case Western Reserve University, USA, 2010.
22.
Bruckner RJ. Performance of simple gas foil thrust bearing in air. Tech. Report, NASA/TM – 2012-217262.
23.
LeeYBKimTYKimCH. Thrust bump air foil bearings with variable axial load: theoretical predictions and experiments. Tribol Trans2011; 54: 902–910.
24.
DykasBBrucknerRJDellaCorteC. Design, fabrication, and performance of foil gas thrust bearings for microturobmachinery applications. J Tribol2009; 131: 012301–012301.
25.
BalducchiFArghirMGauthierR. Experimental analysis of the start-up torque of a mildly loaded foil thrust bearing. J Tribol2013; 135: 031702–031702.
26.
KuCRHeshmatH. Compliant foil bearing structural stiffness analysis: Part I– Theoretical model including strip and variable bump foil geometry. J Tribol1992; 114: 394–400.
SalehiMHeshmatH. On the fluid flow and thermal analysis of a compliant surface foil bearing and seal. Tribol Trans2000; 43: 318–324.
29.
SalehiMSwansonEHeshmatH. Thermal features of compliant foil bearings – theory and experiments. J Tribol2001; 123: 566–571.
30.
WalowitJAAnnoJN. Modern developments in lubrication mechanics, London: Applied Science Publishers Ltd, 1975.
31.
Le LezSArghirMFreneJ. A new bump-type bearing structure analytical model. J Eng Gas Turbines Power2007; 129: 1047–1057.
32.
FengKKanekoS. Analytical model of bump-type foil bearings using a link-spring structure and a finite-element shell model. J Tribol2010; 132: 021706–021706.
33.
HryniewiczPWodtkeMOlszewskiA. Structural properties of foil bearings: a closed-form solution validated with finite element analysis. Tribol Trans2009; 52: 435–446.
34.
Kim D, Ezeka C and Kumar M. Revisit to stiffness of bump foils in air foil bearings. In: ASME/STLE international joint tribology conference, San Diego, California, USA; October 22–24, 2007, paper no. IJTC2007-44319.
35.
PengZCKhonsariMM. On the limiting load-carrying capacity of foil bearings. J Tribol2004; 126: 817–818.
36.
KuCRHeshmatH. Compliant foil bearing structural stiffness analysis: Part II – Experimental investigation. J Tribol1993; 115: 364–369.
