Research Papers

Prediction of Rotordynamic Performance of Smooth Stator-Grooved Rotor Liquid Annular Seals Utilizing Computational Fluid Dynamics

[+] Author and Article Information
Farzam Mortazavi

Department of Mechanical Engineering,
Texas A&M University,
College Station, TX 77843
e-mail: farzam.mortazavi@tamu.edu

Alan Palazzolo

Fellow ASME
Department of Mechanical Engineering,
Texas A&M University,
College Station, TX 77843
e-mail: a-palazzolo@tamu.edu

Contributed by the Technical Committee on Vibration and Sound of ASME for publication in the JOURNAL OF VIBRATION AND ACOUSTICS. Manuscript received July 10, 2017; final manuscript received November 1, 2017; published online December 12, 2017. Assoc. Editor: Patrick S. Keogh.

J. Vib. Acoust 140(3), 031002 (Dec 12, 2017) (9 pages) Paper No: VIB-17-1313; doi: 10.1115/1.4038437 History: Received July 10, 2017; Revised November 01, 2017

Circumferentially grooved, annular liquid seals typically exhibit good whirl frequency ratios (WFRs) and leakage reduction, yet their low effective damping can lead to instability. The current study investigates the rotordynamic behavior of a 15-step groove-on-rotor annular liquid seal by means of computational fluid dynamics (CFD), in contrast to the previous studies which focused on a groove-on-stator geometry. The seal dimensions and working conditions have been selected based on experiments of Moreland and Childs (2016, “Influence of Pre-Swirl and Eccentricity in Smooth Stator/Grooved Rotor Liquid Annular Seals, Measured Static and Rotordynamic Characteristics,” M.Sc. thesis, Texas A&M University, College Station, TX). The frequency ratios as high as four have been studied. Implementation of pressure-pressure inlet and outlet conditions make the need for loss coefficients at the entrance and exit of the seal redundant. A computationally efficient quasi-steady approach is used to obtain impedance curves as functions of the excitation frequency. The effectiveness of steady-state CFD approach is validated by comparison with the experimental results of Moreland and Childs. Results show good agreement in terms of leakage, preswirl ratio (PSR), and rotordynamic coefficients. It was found that PSR will be about 0.3–0.4 at the entrance of the seal in the case of radial injection, and outlet swirl ratio (OSR) always converges to values near 0.5 for current seal and operational conditions. The negative value of direct stiffness coefficients, large cross-coupled stiffness coefficients, and small direct damping coefficients explains the destabilizing nature of these seals. Finally, the influence of surface roughness on leakage, PSR, OSR, and stiffness coefficients is discussed.

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Untaroiu, A. , Morgan, N. , Hayrapetian, V. , and Schiavello, B. , 2017, “ Dynamic Response Analysis of Balance Drum Labyrinth Seal Groove Geometries Optimized for Minimum Leakage,” ASME J. Vib. Acoust., 139(2), p. 021014. [CrossRef]
Moreland, J. A. , and Childs, D. W., 2016, “Influence of Pre-Swirl and Eccentricity in Smooth Stator/Grooved Rotor Liquid Annular Seals, Measured Static and Rotordynamic Characteristics,” M.Sc. thesis, Texas A&M University, College Station, TX. http://oaktrust.library.tamu.edu/handle/1969.1/158918
Childs, D. W. , 2013, Turbomachinery Rotordynamics With Case Studies, Minter Spring, Wellborn, TX.
Marquette, O. R. , Childs, D. W. , and Phillips, S. G. , 1997, “Theory Versus Experiment for Leakage and Rotordynamic Coefficients of Circumferentially-Grooved Liquid Annular Seals With L/D of 0.45,” ASME Paper No. FED SM97-3333.
Massey, I. , 1985, “ Subsynchronous Vibration Problems in High-Speed Multistage Centrifugal Pumps,” 14th Turbomachinery Symposium, Houston, TX, Oct., pp. 11–16. http://oaktrust.library.tamu.edu/handle/1969.1/163638
Lomakin, A. , 1958, “ Calculation of Critical Number of Revolutions and the Conditions Necessary for Dynamic Stability of Rotors in High-Pressure Hydraulic Machines When Taking Into Account Forces Originating in Sealings,” Power Mech. Eng., 14(4), pp. 1–5 (in Russian).
Iwatsubo, T. , and Sheng, B. , 1990, “ Evaluation of Dynamic Characteristics of Parallel Grooved Seals by Theory and Experiment,” Third IFToMM International Conference on Rotordynamics, Lyon, France, pp. 313–318.
Marquette, O. R. , and Childs, D. W. , 1996, “ An Extended Three-Control-Volume Theory for Circumferentially-Grooved Liquid Seals,” ASME J. Tribol., 118(2), pp. 276–285. [CrossRef]
Hirs, G. G. , 1973, “ A Bulk-Flow Theory for Turbulence in Lubricant Films,” ASME J. Lubr. Technol., 95(2), pp. 137–146. [CrossRef]
Dietzen, F. J. , and Nordmann, R. , 1987, “ Calculating Rotordynamic Coefficients of Seals by Finite-Difference Techniques,” ASME J. Tribol., 109(3), pp. 388–394. [CrossRef]
Dietzen, F. J. , and Nordmann, R. , 1988, “ A 3-Dimensional Finite-Difference Method for Calculating the Dynamic Coefficients of Seals,” Rotordynamic Instability Problems in High-Performance Turbomachinery, College Station, TX, May 16–18, pp. 211–227. https://ntrs.nasa.gov/search.jsp?R=19890013532
Moore, J. J. , and Palazzolo, A. B. , 2001, “ Rotordynamic Force Prediction of Whirling Centrifugal Impeller Shroud Passages Using Computational Fluid Dynamic Techniques,” ASME J. Eng. Gas Turbines Power, 123(4), pp. 910–918. [CrossRef]
Moore, J. J. , and Palazzolo, A. B. , 1999, “ CFD Comparison to 3D Laser Anemometer and Rotordynamic Force Measurements for Grooved Liquid Annular Seals,” ASME J. Tribol., 121(2), pp. 306–314. [CrossRef]
Moore, J. J. , 2003, “ Three-Dimensional CFD Rotordynamic Analysis of Gas Labyrinth Seals,” ASME J. Vib. Acoust., 125(4), pp. 427–433. [CrossRef]
Untaroiu, A. , Untaroiu, C. D. , Wood, H. G. , and Allaire, P. E. , 2012, “ Numerical Modeling of Fluid-Induced Rotordynamic Forces in Seals With Large Aspect Ratios,” ASME J. Eng. Gas Turbines Power, 135(1), p. 012501. [CrossRef]
Meng, Z. , Xiao-Fang, W. , Sheng-Li, X. , and Wei, W. , 2013, “ Numerical Simulation of the Flow Field in Circumferential Grooved Liquid Seals,” Adv. Mech. Eng., 5, p. 797201. [CrossRef]
Li, Z. , Li, J. , and Yan, X. , 2013, “ Multiple Frequencies Elliptical Whirling Orbit Model and Transient RANS Solution Approach to Rotordynamic Coefficients of Annual Gas Seals Prediction,” ASME J. Vib. Acoust., 135(3), p. 031005. [CrossRef]
Moreland, J. A. , Childs, D. W. , and Bullock, J. T. , 2017, “Measured Static Rotordynamic Characteristics a Smooth-Stator/Grooved-Rotor Liquid Annular Seal,” ASME Paper No. FEDSM2017-69036.
Glienicke, J. , 1966, “ Experimental Investigation of Stiffness and Damping Coefficients of Turbine Bearings and Their Application to Instability Prediction,” Inst. Mech. Eng.—Proc. J. Bearings Reciprocating Turbo Mach., 181(2), pp. 116–129.
Yan, X. , Li, J. , and Feng, Z. , 2011, “ Investigations on the Rotordynamic Characteristics of a Hole-Pattern Seal Using Transient CFD and Periodic Circular Orbit Model,” ASME J. Vib. Acoust., 133(4), p. 041007. [CrossRef]
Kim, E. , and Palazzolo, A. , 2016, “ Rotordynamic Force Prediction of a Shrouded Centrifugal Pump Impeller—Part I: Numerical Analysis,” ASME J. Vib. Acoust., 138(3), p. 031014. [CrossRef]
Untaroiu, A. , Wood, H. G. , Migliorini, P. , Allaire, P. E. , and Kocur, J. A., Jr. , 2009, “Hole-Pattern Seals: A Three Dimensional CFD Approach for Computing Rotordynamic Coefficient and Leakage Characteristics,” ASME Paper No. IMECE2009-11558.
Childs, D. , and Hale, K. , 1994, “ Test Apparatus and Facility to Identify the Rotordynamic Coefficients of High-Speed Hydrostatic Bearings,” ASME J. Tribol., 116(2), pp. 337–344. [CrossRef]
Smirnov, P. E. , and Menter, F. R. , 2009, “ Sensitization of the SST Turbulence Model to Rotation and Curvature by Applying the Spalart-Shur Correction Term,” ASME J. Turbomach., 131(4), p. 041010. [CrossRef]
Balasubramanian, R. , and Barrows, S. , 2008, “Investigation of Shear-Stress Transport Turbulence Model for Turbomachinery Applications,” AIAA Paper No. AIAA 2008-566.
Nikparto, A. , and Schobeiri, M. T. , 2017, “Investigation of Aerodynamics and Heat Transfer of a Highly Loaded Turbine Blade Using the Universal Intermittency Function,” ASME Paper No. GT2017-64988.
Schobeiri, M. T. , and Nikparto, A. , 2014, “A Comparative Numerical Study of Aerodynamics and Heat Transfer on Transitional Flow around a Highly Loaded Turbine Blade With Flow Separation Using RANS, URANS and LES,” ASME Paper No. GT2014-25828.
Schobeiri, M. T. , and Ghoreyshi, S. M. , 2015, “ The Ultrahigh Efficiency Gas Turbine Engine With Stator Internal Combustion,” ASME J. Eng. Gas Turbines Power, 138(2), p. 021506. [CrossRef]
Mortazavi, F. , Riasi, A. , and Nourbakhsh, A. , 2017, “ Numerical Investigation of Back Vane Design and Its Impact on Pump Performance,” ASME J. Fluids Eng., 139(12), p. 121104. [CrossRef]
Storteig, E. , 2000, “Dynamic Characteristics and Leakage Performance of Liquid Annular Seals in Centrifugal Pumps,” Ph.D. dissertation, Norwegian University of Science and Technology, Trondheim, Norway. https://brage.bibsys.no/xmlui/handle/11250/231234
ANSYS, 2016, “ANSYS CFX-Solver Theory Guide,” ANSYS, Inc., Canonsburg, PA.
Childs, D. W. , and Fayolle, P. , 1999, “ Test Results for Liquid ‘Damper’ Seals Using a round-Hole Roughness Pattern for the Stators,” ASME J. Tribol., 121(1), pp. 42–49. [CrossRef]


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Fig. 1

Negative stiffness

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Fig. 2

Schematic of the seal dimensions

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Fig. 3

Quasi-steady circular whirling motion in CFD modeling

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Fig. 4

Computational domains used for CFD simulation

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Fig. 5

Exploded view of the grid

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Fig. 7

Suppressed back flow and the streamlines at the inlet chamber

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Fig. 8

Flow reattachment in extension annulus

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Fig. 9

Pressure and swirl ratio variation at r=50.9mm in the inlet plenum, seal, and outlet chamber

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Fig. 10

Leakage, PSR, and OSR versus frequency ratio

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Fig. 11

Dynamic stiffness variation versus excitation frequency: (a) (Hii), (b) Re(Hij), (c) Im(Hii), and (d) Im(Hij)

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Fig. 12

Radial and tangential forces acting on the rotor

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Fig. 13

Effect of rotor speed on leakage

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Fig. 14

Effect of Δp on leakage

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Fig. 15

Effect of roughness on leakage, PSR, and OSR

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Fig. 16

Effect of roughness on radial and tangential impedance at Ω=0




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