Gas foil bearings offer several advantages over traditionalbearing types that make them attractive for use in high-speedturbomachinery. They can operate at very high temperatures,require no lubrication supply (oil pumps, seals, etc.), exhibitvery long life with no maintenance, and once operatingairborne, have very low power loss. The use of gas foil bearingsin high-speed turbomachinery has been accelerating in recentyears, although the pace has been slow. One of the contributingfactors to the slow growth has been a lack of analysis tools,benchmarked to measurements, to predict gas foil bearingbehavior in rotating machinery. To address this shortcoming,NASA Glenn Research Center (GRC) has supported thedevelopment of analytical tools to predict gas foil bearingperformance. One of the codes has the capability to predictrotordynamic coefficients, power loss, film thickness, structuraldeformation, and more. The current paper presents anassessment of the predictive capability of the code, namedXLGFBTH (Texas A&M University). A test rig at GRC is usedas a simulated case study to compare rotordynamic analysisusing output from the code to actual rotor response as measuredin the test rig. The test rig rotor is supported on two gas foiljournal bearings manufactured at GRC, with all pertinentgeometry disclosed. The resulting comparison shows that therotordynamic coefficients calculated using XLGFBTH representthe dynamics of the system reasonably well, especially as theypertain to predicting critical speeds.
Gas foil bearings offer several advantages over traditional<br>bearing types that make them attractive for use in high-speed<br>turbomachinery. They can operate at very high temperatures,<br>require no lubrication supply (oil pumps, seals, etc.), exhibit<br>very long life with no maintenance, and once operating<br>airborne, have very low power loss. The use of gas foil bearings<br>in high-speed turbomachinery has been accelerating in recent<br>years, although the pace has been slow. One of the contributing<br>factors to the slow growth has been a lack of analysis tools,<br>benchmarked to measurements, to predict gas foil bearing<br>behavior in rotating machinery. To address this shortcoming,<br>NASA Glenn Research Center (GRC) has supported the<br>development of analytical tools to predict gas foil bearing<br>performance. One of the codes has the capability to predict<br>rotordynamic coefficients, power loss, film thickness, structural<br>deformation, and more. The current paper presents an<br>assessment of the predictive capability of the code, named<br>XLGFBTH (Texas A&M University). A test rig at GRC is used<br>as a simulated case study to compare rotordynamic analysis<br>using output from the code to actual rotor response as measured<br>in the test rig. The test rig rotor is supported on two gas foil<br>journal bearings manufactured at GRC, with all pertinent<br>geometry disclosed. The resulting comparison shows that the<br>rotordynamic coefficients calculated using XLGFBTH represent<br>the dynamics of the system reasonably well, especially as they<br>pertain to predicting critical speeds.
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