Force coefficients for a large clearance open ends squeeze film damper with a central feed groove: Experiments and predictions |
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Affiliation: | 1. School of Mechanical and Precision Instrument Engineering, Xi’an University of Technology, Xi’an 710048, Shaanxi, PR China;2. State Key Laboratory for Strength and Vibration of Mechanical Structures, Xi’an Jiaotong University, Xi’an 710049, Shaanxi, PR China;3. Department of Mechanical and Electrical Engineering, Shaanxi Railway Institute, Wei Nan 714000, Shaanxi, PR China;4. College of Engineering, Michigan State University, East Lansing, MI 48824, USA;5. School of Printing and Packaging Engineering, Xi’an University of Technology, Xi’an 710048, Shaanxi, PR China;6. Robert R. McCormick School of Engineering and Applied Science, Northwestern University, Evanston, IL 60208, USA;1. School of Astronautics, Harbin Institute of Technology, Harbin 150001, PR China;2. School of Energy Science and Engineering, Harbin Institute of Technology, Harbin 150001, PR China |
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Abstract: | The paper describes a large load squeeze film damper (SFD) test rig, details measurements of dynamic loads inducing circular orbits conducted on a large clearance (c=0.250 mm) open ends centrally grooved SFD, and presents the identified experimental SFD force coefficients for operation at three static eccentricities. The rig has a bearing cartridge supported atop four elastic rods and a stationary journal, 0.127 mm in diameter. The damper consists of two parallel film lands, 12.7 mm in length, separated by a central groove, 6.35 mm 9.5 mm in depth. In the journal, three equally spaced holes, 120° apart, supply a light lubricant into the central groove and squeeze film lands. The experimental SFD force coefficients are compared to test results obtained earlier for a damper with the same film land lengths but with a smaller clearance (c=0.140 mm) and against predictions obtained from an advanced physical model that accounts for the flow field in the central groove and the interaction with the adjacent film lands. Dynamic pressures in the film lands and in the central groove are (not) surprisingly of the same order of magnitude. The central groove affects the dynamic forced response of the test damper to generate large direct damping coefficients, ~3.5 times those derived from classical lubrication formulas. Experimental added mass coefficients are ~7.4 times the predictive classical values. Predictions from an advanced model correlate well with the test data when using a shallow groove depth. The measurements and analysis advance knowledge on the dynamic forced performance of SFDs, point out to the limited value of simplistic predictive formulas, and validate the accuracy of a modern predictive tool. |
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Keywords: | Squeeze film damper Hydrodynamic lubrication Rotordynamics Vibrations |
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