Transient Response of a Short-Length (L/D=0.2) Open-Ends Elastically Supported Squeeze Film Damper: Centered and Largely Off-Centered Whirl Motions

Significance Statement

Turbomachinery such as centrifugal compressors and aircraft engines will undergo startups/shutdowns and traverse critical speeds. While in operation, turbomachinery may also experience sudden maneuver loads, loss of lift due to turbulence or interruption in lubricant supply, or even blade loss events that trigger large amplitude rotor vibration. Squeeze film dampers (SFDs) reduce the amplitude of rotor vibration during these transient events and enhance system stability and structural isolation of the rotor.

Prior to startups and while at rest, rotors and dampers may sit at their clearance bottom, which may be in contact with the engine’s housing. As the engine accelerates, hydrodynamic pressure produced in the lubricant film lifts the rotor/damper and displaces it away from the housing. Until the rotor is centered within the clearance, however, the housing and supporting structures fatigue from large cyclical transmitted loads emanating from asymmetrical and skewed orbits of the rotor. Furthermore, during an aircraft hard landing, loss of lift, or blade loss event, the rotor-bearing system undergoes large elliptical whirl orbits that are also severely off-centered within the available clearance and consequently experiences large amplitude transmitted loads as well.

In their publication in Journal of Engineering for Gas Turbines and Power Professor Luis San Andrés led a team of researchers in presenting the findings from an elastically supported short-length SFD operating during transient conditions with movements originating from large static eccentricities. The authors composed an experiment that quantified dynamic performance of a SFD exposed to centered and off-centered whirl orbits initiated by various combinations of dynamic and static loads. They measured the SFD displacements, accelerations, and oil film pressures that were central to characterizing the response of the damper while crossing two system natural frequencies.

Among the experimental findings, some of the more interesting observations were that the amplitude of the motions from the off-centered operation was smaller compared to that of motions from the centered position. This was owing to the large damping produced by a small lubricant film thickness that exists in an off-centered position. Also the SFD, for off-centered positions, exhibited lower resonance frequencies when compared to the frequencies for centered operation.

findings, along with others highlighted in their article, enabled the authors to demonstrate that SFDs can effectively control a rotor-bearing system’s amplitude of vibration in response to several operating conditions and even during transient conditions – for instance an engine start-up from an off-centered rotor position.

Transient Response of a Short-Length (LD=0.2) Open-Ends Elastically Supported Squeeze Film Damper Centered and Largely Off-Centered Whirl Motions-advances in engineering

About The Author

Luis San Andrés is a renowned analyst and experimentalist in the fields of fluid film lubrication and rotordynamics. Dr. San Andrés has performed research on the analysis and experimental verification of gas foil bearing performance for high temperature oil free turbomachinery and squeeze film dampers for aircraft jet engines. His computational codes, benchmarked against test data, are standards in the rotating machinery industry. Dr. San Andrés and his students have published over 160 papers, several earning best paper awards.

Prof. San Andrés is an ASME Fellow and STLE Fellow, a member of the Advisory Committee for the Houston-Turbomachinery Symposium, and Chair of the Asia Turbomachinery Symposium.

About The Author

Sean Den is currently a mechanical maintenance engineer at Formosa Plastics Corporation and is assigned to the FPCTX plant’s Utilities Department where he oversees the reliability of various equipment including 6 gas turbines and 5 steam turbines. Prior to his position at Formosa, Sean graduated with a B.S. in Bioengineering at Rice University in 2013 and M.S. in Mechanical Engineering at Texas A&M University in 2015. While at Texas A&M, Sean performed research in the design of bearings and seals with a focus on lubrication and vibration analysis under the guidance of Dr. Luis San Andrés. Sean’s research findings in the field of turbomachinery have led him to publish papers in both ASME and the Turbomachinery&Pump Symposium.

About The Author

Sung-Hwa Jeung is currently the rotating equipment design engineer for Compressor Technology & Development at Ingersoll-Rand. He received a B.S. degree in Mechanical Engineering from Korea University (Seoul) in 2010. Immediately after graduation, he worked as a mechanical engineer at Hyundai Engineering Co., LTD. before pursuing his graduate studies at Texas A&M University. He received a M.S. degree in Mechanical Engineering from Texas A&M University in 2013 and expects to earn his Ph.D. degree in May, 2017. During the course of his research, he has authored several papers in ASME conferences and journals, having won the Best Paper at the (2014) IFToMM International Conference on Rotordynamics. His research mainly focuses on fluid film lubrication and rotordynamics in turbomachinery, in particular, experimental identification of forced performance of squeeze film dampers.

Reference

Luis San Andres1, Sean Den2, and Sung-Hwa Jeung3. Transient response of a short length (L/D=50.2) open-ends elastically supported squeeze film damper: centered and largely off-centered whirl motions. Journal of Engineering for Gas Turbines and Power, volume 138 (2016).

Show Affiliations
  1. Mast–Childs Chair Professor, Fellow ASME, Turbomachinery Laboratory,
    Mechanical Engineering Department, Texas A&M University, College Station, TX 77843
  2. Mechanical Maintenance Engineer, Formosa Plastics Corp., Point Comfort, TX 77978
  3. Graduate Research Assistant, Turbomachinery Laboratory, Mechanical Engineering Department, Texas A&M University, College Station, TX 77843

 

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