A successful implementation of gas foil bearings (GFBs) into high temperature turbomachinery requires adequate thermal management to maintain system reliability and stability. The most common approach for thermal management in a GFB-rotor system is to supply pressurized air at one end of the bearing to remove hot spots in the bearings and control thermal growth of components. This technical brief presents test data for a laboratory rotor-GFB system operating hot to identify the flow characteristics of axial cooling streams flowing through the thin film region and underneath the top foil. A bulk flow model is used for description of the fluid motion and includes the Hirs’ friction factor formulation for smooth surfaces. Laminar flow prevails through the thin film gas region; while for the cooling flow between the top foil and bearing housing, a transition from laminar flow to turbulent flow occurs as the cooling flow rate increases. Large cooling flow rate and the ensuing turbulent flow conditions render limited effectiveness in controlling temperatures in a test rotor-GFB system.

References

References
1.
Dykas
,
B. D.
, 2006, “
Factors Influencing the Performance of Foil Gas Thrust Bearings for Oil-Free Turbomachinery Applications
,” Ph.D. dissertation, Case Western Reserve University, Cleveland, OH.
2.
Radil
,
K. C.
,
DellaCorte
,
C.
, and
Zeszotek
,
M.
, 2007, “
Thermal Management Techniques for Oil-Free Turbomachinery Systems
,”
STLE Tribol. Trans.
,
50
(
3
), pp.
319
327
.
3.
Radil
,
K.
, and
Batcho
,
Z.
, 2011, “
Air Injection as a Thermal Management Technique for Radial Foil Air Bearings
,”
STLE Tribol. Trans.
,
54
(
4
), pp.
666
673
.
4.
San Andrés
,
L.
,
Kim
,
T. H.
, and
Ryu
,
K.
, 2009, “
Thermohydrodynamic Analysis of Bump Type Gas Foil Bearings: A Model Anchored to Test Data
,” Final Project Report to NASA SSRW2-1.3 Oil Free Engine Technology Program.
5.
Ryu
,
K.
, 2011, “
Effect of Cooling Flow on the Operation of a Hot Rotor-Gas Foil Bearing System
,” Ph.D. dissertation, Texas A&M University, College Station, TX.
6.
San Andrés
,
L.
, and
Kim
,
T. H.
, 2010, “
Thermohydrodynamic Analysis of Bump Type Gas Foil Bearings: A Model Anchored to Test Data
,”
ASME J. Eng. Gas Turbines Power
,
132
(
4
), p.
042504
.
7.
Heshmat
,
H.
,
Tomaszewski
,
M.
, and
Walton
,
J. F.
, 2006, “
Small Gas Turbine Engine Operating With High Temperature Foil Bearings
,” ASME Paper No. GT2006-90791.
8.
San Andrés
,
L.
,
Ryu
,
K.
, and
Kim
,
T. H.
, 2011, “
Identification of Structural Stiffness and Energy Dissipation Parameters in a Second Generation Foil Bearing—Effect of Shaft Temperature
,”
ASME J. Eng. Gas Turbines Power
,
133
(
3
), p.
032501
.
9.
Fox
,
R. W.
,
McDonald
,
A. T.
, and
Pritchard
,
P. J.
, 2004,
Introduction to Fluid Mechanics
,
6th ed.
,
Wiley, Hoboken
,
NJ
, pp.
720
722
.
10.
Hirs
,
G. G.
, 1973, “
A Bulk-Flow Theory for Turbulence in Lubricant Films
,”
ASME J. Lubr. Technol.
,
95
(
2
), pp.
137
146
.
11.
Zirkelback
,
N.
, and
San Andrés
,
L.
, 1996, “
Bulk-Flow Model for the Transition to Turbulent Regime in Annular Pressure Seals
,”
STLE Tribol. Trans.
,
39
(
4
), pp.
835
842
.
12.
Nelson
,
C. C.
, and
Nguyen
,
D. T.
, 1987, “
Comparison of Hirs’ Equation With Moody’s Equation for Determining Rotordynamic Coefficients of Annular Pressure Seals
,”
ASME J. Tribol.
,
109
(
1
), pp.
144
148
.
13.
Black
,
H. F.
,
Allaire
,
P. E.
, and
Barrett
,
L. E.
, 1981, “
Inlet Flow Swirl in Short Turbulent Annular Seal Dynamics
,”
Proceedings of the Ninth International Conference in Fluid Sealing
, April 1–3,
BHRA Fluid Engineering, Leeuwenborst
,
The Netherlands
, pp.
141
152
.
14.
Kim
,
T. H.
, and
San Andrés
,
L.
, 2009, “
Effect of Side End Pressurization on the Dynamic Performance of Gas Foil Bearings—A Model Anchored to Test Data
,”
ASME J. Eng. Gas Turbines Power
,
131
, p.
012501
.
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