Annular gas seals for compressors and turbines are designed to operate in a nominally centered position in which the rotor and stator are at concentric condition, but due to the rotor–stator misalignment or flexible rotor deflection, many seals usually are suffering from high eccentricity. The centering force (represented by static stiffness) of an annular gas seal at eccentricity plays a pronounced effect on the rotordynamic and static stability behavior of rotating machines. The paper deals with the leakage and static stability behavior of a fully partitioned pocket damper seal (FPDS) at high eccentricity ratios. The present work introduces a novel mesh generation method for the full 360 deg mesh of annular gas seals with eccentric rotor, based on the mesh deformation technique. The leakage flow rates, static fluid-induced response forces, and static stiffness coefficients were solved for the FPDS at high eccentricity ratios, using the steady Reynolds-averaged Navier–Stokes solution approach. The calculations were performed at typical operating conditions including seven rotor eccentricity ratios up to 0.9 for four rotational speeds (0 rpm, 7000 rpm, 11,000 rpm, and 15,000 rpm) including the nonrotating condition, three pressure ratios (0.17, 0.35, and 0.50) including the choked exit flow condition, two inlet preswirl velocities (0 m/s, 60 m/s). The numerical method was validated by comparisons to the experiment data of static stiffness coefficients at choked exit flow conditions. The static direct and cross-coupling stiffness coefficients are in reasonable agreement with the experiment data. An interesting observation stemming from these numerical results is that the FPDS has a positive direct stiffness as long as it operates at subsonic exit flow conditions; no matter the eccentricity ratio and rotational speed are high or low. For the choked exit condition, the FPDS shows negative direct stiffness at low eccentricity ratio and then crosses over to positive value at the crossover eccentricity ratio (0.5–0.7) following a trend indicative of a parabola. Therefore, the negative static direct stiffness is limited to the specific operating conditions: choked exit flow condition and low eccentricity ratio less than the crossover eccentricity ratio, where the pocket damper seal (PDS) would be statically unstable.
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April 2018
Research-Article
Numerical Investigation on the Leakage and Static Stability Characteristics of Pocket Damper Seals at High Eccentricity Ratios
Zhigang Li,
Zhigang Li
Institute of Turbomachinery,
School of Energy and Power Engineering,
Xi’an Jiaotong University,
Xi’an 710049, China
School of Energy and Power Engineering,
Xi’an Jiaotong University,
Xi’an 710049, China
Search for other works by this author on:
Jun Li,
Jun Li
Institute of Turbomachinery,
School of Energy and Power Engineering,
Xi’an Jiaotong University,
Xi’an 710049, China;
Collaborative Innovation Center
of Advanced Aero-Engine,
Beijing 100191, China
e-mail: junli@mail.xjtu.edu.cn
School of Energy and Power Engineering,
Xi’an Jiaotong University,
Xi’an 710049, China;
Collaborative Innovation Center
of Advanced Aero-Engine,
Beijing 100191, China
e-mail: junli@mail.xjtu.edu.cn
Search for other works by this author on:
Zhenping Feng
Zhenping Feng
Institute of Turbomachinery,
School of Energy and Power Engineering,
Xi’an Jiaotong University,
Xi’an 710049, China
School of Energy and Power Engineering,
Xi’an Jiaotong University,
Xi’an 710049, China
Search for other works by this author on:
Zhigang Li
Institute of Turbomachinery,
School of Energy and Power Engineering,
Xi’an Jiaotong University,
Xi’an 710049, China
School of Energy and Power Engineering,
Xi’an Jiaotong University,
Xi’an 710049, China
Jun Li
Institute of Turbomachinery,
School of Energy and Power Engineering,
Xi’an Jiaotong University,
Xi’an 710049, China;
Collaborative Innovation Center
of Advanced Aero-Engine,
Beijing 100191, China
e-mail: junli@mail.xjtu.edu.cn
School of Energy and Power Engineering,
Xi’an Jiaotong University,
Xi’an 710049, China;
Collaborative Innovation Center
of Advanced Aero-Engine,
Beijing 100191, China
e-mail: junli@mail.xjtu.edu.cn
Zhenping Feng
Institute of Turbomachinery,
School of Energy and Power Engineering,
Xi’an Jiaotong University,
Xi’an 710049, China
School of Energy and Power Engineering,
Xi’an Jiaotong University,
Xi’an 710049, China
1Corresponding author.
Contributed by the Structures and Dynamics Committee of ASME for publication in the JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER. Manuscript received July 23, 2017; final manuscript received August 1, 2017; published online November 7, 2017. Editor: David Wisler.
J. Eng. Gas Turbines Power. Apr 2018, 140(4): 042503 (16 pages)
Published Online: November 7, 2017
Article history
Received:
July 23, 2017
Revised:
August 1, 2017
Citation
Li, Z., Li, J., and Feng, Z. (November 7, 2017). "Numerical Investigation on the Leakage and Static Stability Characteristics of Pocket Damper Seals at High Eccentricity Ratios." ASME. J. Eng. Gas Turbines Power. April 2018; 140(4): 042503. https://doi.org/10.1115/1.4038081
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