This paper presents measured frequency dependent stiffness and damping coefficients for 12-bladed and 8-bladed pocket damper seals (PDS) subdivided into four different seal configurations. Rotating experimental tests are presented for inlet pressures at 69 bar (1000 psi), a frequency excitation range of 20–300 Hz, and rotor speeds up to 20,200 rpm. The testing method used to determine direct and cross-coupled force coefficients was the mechanical impedance method, which required the measurement of external shaker forces, system accelerations, and motion in two orthogonal directions. In addition to the impedance measurements, dynamic pressure responses were measured for individual seal cavities of the eight-bladed PDS. Results of the frequency dependent force coefficients for the four PDS designs are compared. The conclusions of the tests show that the eight-bladed PDS possessed significantly more positive direct damping and negative direct stiffness than the 12-bladed seal. The results from the dynamic pressure response tests show that the diverging clearance design strongly influences the dynamic pressure phase and force density of the seal cavities. The tests also revealed the measurement of same-sign cross-coupled (cross-axis) stiffness coefficients for all seals, which indicate that the seals do not produce a destabilizing influence on rotor-bearing systems.
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e-mail: ertas@research.ge.com
e-mail: ajmg@tamu.edu
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October 2006
Technical Papers
Rotordynamic Force Coefficients of Pocket Damper Seals
B. Ertas,
B. Ertas
Vibrations/Dynamics Laboratory,
e-mail: ertas@research.ge.com
Rotating Equipment Group
, GE Global Research, 1 Research Circle, Niskayuna, NY 12309
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A. Gamal,
A. Gamal
Mechanical Engineering Department,
e-mail: ajmg@tamu.edu
Texas A&M University
, College Station, TX 77843-3123
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J. Vance
J. Vance
Mechanical Engineering Department,
e-mail: jvance@tamu.edu
Texas A&M University
, College Station, TX 77843-3123
Search for other works by this author on:
B. Ertas
Vibrations/Dynamics Laboratory,
Rotating Equipment Group
, GE Global Research, 1 Research Circle, Niskayuna, NY 12309e-mail: ertas@research.ge.com
A. Gamal
Mechanical Engineering Department,
Texas A&M University
, College Station, TX 77843-3123e-mail: ajmg@tamu.edu
J. Vance
Mechanical Engineering Department,
Texas A&M University
, College Station, TX 77843-3123e-mail: jvance@tamu.edu
J. Turbomach. Oct 2006, 128(4): 725-737 (13 pages)
Published Online: February 1, 2006
Article history
Received:
October 1, 2005
Revised:
February 1, 2006
Citation
Ertas, B., Gamal, A., and Vance, J. (February 1, 2006). "Rotordynamic Force Coefficients of Pocket Damper Seals." ASME. J. Turbomach. October 2006; 128(4): 725–737. https://doi.org/10.1115/1.2221327
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