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Fluid-Structure Interaction

Fluidelastic Instability Modeling of Loosely Supported Multispan U-Tubes in Nuclear Steam Generators

[+] Author and Article Information
Marwan Hassan

Flow-Induced Vibrations Laboratory
School of Engineering
University of Guelph
Guelph, ON, N1G 2W1, Canada
e-mail: mahassan@uoguelph.ca

Atef Mohany

Fluid-Sound-Structure Interaction Laboratory
Automotive Center of Excellence
University of Ontario Institute of Technology
Oshawa, ON, L1H 7K4, Canada
e-mail: Atef.Mohany@uoit.ca

1Corresponding author.

Contributed by the Pressure Vessel and Piping Division of ASME for publication in the JOURNAL OF PRESSURE VESSEL TECHNOLOGY. Manuscript received October 30, 2011; final manuscript received March 6, 2012; published online December 5, 2012. Assoc. Editor: Jong Chull Jo.

J. Pressure Vessel Technol 135(1), 011306 (Dec 05, 2012) (9 pages) Paper No: PVT-11-1193; doi: 10.1115/1.4006854 History: Received October 30, 2011; Revised March 06, 2012

Steam generators in nuclear power plants have experienced tube failures caused by flow-induced vibrations. Two excitation mechanisms are responsible for such failures; random turbulence excitation and fluidelastic instability. The random turbulence excitation mechanism results in long-term failures due to fretting-wear damage at the tube supports, while fluidelastic instability results in short-term failures due to excessive vibration of the tubes. Such failures may require shutdowns, which result in production losses, and pose potential threats to human safety and the environment. Therefore, it is imperative to predict the nonlinear tube response and the associated fretting-wear damage to tubes due to fluid excitation. In this paper, a numerical model is developed to predict the nonlinear dynamic response of a steam generator with multispan U-tubes and anti-vibration bar supports, and the associated fretting wear due to fluid excitation. Both the crossflow turbulence and fluidelastic instability forces are considered in this model. The finite element method is utilized to model the vibrations and impact dynamics. The tube bundle geometry is similar to the geometry used in CANDU steam generators. Eight sets of flat-bar supports are considered. Moreover, the effect of clearances between the tubes and their supports, and axial offset between the supports are investigated. The results are presented and comparisons are made for the parameters influencing the fretting-wear damage, such as contact ratio, impact forces, and normal work rate. It is clear that tubes in loose flat-bar supports have complex dynamics due to a combination of geometry, tube-to-support clearance, offset, and misalignment. However, the results of the numerical simulation along with the developed model provide new insight into the flow-induced vibration mechanism and fretting wear of multispan U-tubes that can be incorporated into future design guidelines for steam generators and large heat exchangers.

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References

Weaver, D., Ziada, S., Au-Yang, M., Chen, S., Païdoussis, M. P., and Pettigrew, M., 2000, “Flow-Induced Vibrations in Power and Process Plant Components—Progress and Prospects,” ASME J. Pressure Vessel Technol., 122, pp. 339–348. [CrossRef]
Pettigrew, M., and Taylor, C., 2003, “Vibration Analysis of Steam Generators and Heat Exchangers: An Overview Part 1: Flow Damping, Fluidelastic Instability,” J. Fluids Struct., 18(5), pp. 469–483. [CrossRef]
Chen, S. S., 1984, “Guidelines for the Instability Flow Velocity of Tube Arrays in Cross-Flow,” J. Sound Vib., 93, pp. 439–455. [CrossRef]
Weaver, D., and Fitzpatrick, J., 1988, “A Review of Cross-Flow Induced Vibrations in Heat Exchanger Tube Arrays,” J. Fluids Struct., 2, pp. 73–93. [CrossRef]
Pettigrew, M., and Taylor, C., 1991, “Fluidelastic Instability of Heat Exchanger Tube Bundles: Review and Design Recommendations,” ASME J. Pressure Vessel Technol., 113(2), pp. 242–256. [CrossRef]
Schröder, K., and Gelbe, H., 1999, “New Design Recommendations for Fluidelastic Instability in Heat Exchanger Tube Bundles,” J. Fluids Struct., 13, pp. 361–379. [CrossRef]
Chen, S. S., 1983, “Instability Mechanisms and Stability Criteria of a Group of Circular Cylinders Subjected to Cross-Flow. Part 1: Theory,” ASME J. Vib., Acoust., Stress, Reliab. Des., 105, pp. 51–58. [CrossRef]
Connors, H. J., 1970, “Fluidelastic Vibration of Tube Arrays Excited by Cross Flow,” Flow-Induced Vibration in Heat Exchangers, D. D.Reiff, ed., ASME, Conference on Flow Induced Vibration in Heat Exchangers; ASME Winter Annual Meeting: New York, pp. 42–57 .
Tanaka, H., and Takahara, S., 1981, “Fluid Elastic Vibration of Tube Array in Cross-Flow,” J. Sound Vib., 77, pp. 19–37. [CrossRef]
Lever, J. H., and Weaver, D. S., 1982, “A Theoretical Model for the Fluidelastic Instability in Heat Exchanger Tube Bundles,” ASME J. Pressure Vessel Technol., 104, pp. 104–147. [CrossRef]
Price, S. J., and Païdoussis, M. P., 1984, “An Improved Mathematical Model for the Stability of Cylinder Rows Subjected to Cross-Flow,” J. Sound Vib., 97(4), pp. 615–640. [CrossRef]
Weaver, D. S., 2008, “Some Thoughts on the Elusive Mechanism of Fluidelastic Instability in Heat Exchanger Tube Arrays,” The 9th International Conference on Flow-Induced Vibration.
Axisa, F., Antunes, J., and Villard, B., 1988, “Overview of Numerical Methods for Predicting Flow-Induced Vibration,” ASME J. Pressure Vessel Technol., 110, pp. 6–14. [CrossRef]
Fricker, A., 1992, “Numerical Analysis of the Fluid-Elastic Vibration of a Steam Generator Tube With Loose Support,” J. Fluids Struct., 6, pp. 85–107. [CrossRef]
Sauvé, R., 1996, “A Computational Time Domain Approach to Fluidelastic Instability for Nonlinear Tube Dynamics,” ASME PVP/ICPVT-8 Conference on Symposium on Flow Induced Vibrations, M.Pettigrew, ed., ASME, New York, pp. 111–121.
Eisinger, F., Rao, M., Steininger, D., and Haslinger, K., 1995, “Numerical Simulation of Cross-Flow Induced Fluidelastic Vibration of Tube Arrays and Comparison With Experimental Results,” ASME J. Pressure Vessel Technol., 111, pp. 378–384. [CrossRef]
Hassan, M., and Hayder, M., 2008, “Modelling of Fluidelastic Vibrations of Heat Exchanger Tubes With Loose Supports,” Nucl. Eng. Des., 238(10), pp. 2507–2520. [CrossRef]
Hassan, M., and Achraf, H., 2010, “Time Domain Models for Damping-Controlled Fluidelastic Instability Forces in Tubes With Loose Supports,” ASME J. Pressure Vessel Technol., 132(4), 041302. [CrossRef]
Yetisir, M., and Weaver, D., 1993, “An Unsteady Theory for Fluidelastic Instability in an Array of Flexible Tubes in Cross-Flow. Part1: Theory,” J. Fluids Struct., 7, pp. 751–766. [CrossRef]
Oengören, A., and Ziada, S., 1998, “An In-Depth Study of Vortex Shedding, Acoustic Resonance and Turbulent Forces in Normal Triangle Tube Arrays,” J. Fluids Struct., 12, pp. 717–758. [CrossRef]
Hassan, M., Weaver, D., and Dokainish, M., 2002, “A Simulation of the Turbulence Response of Heat Exchanger Tubes in Lattice-Bar Supports,” J. Fluids Struct., 16(8), pp. 1145–1176. [CrossRef]
Morandin, G. D., and Sauvé, R. G., 2003, “Probabilistic Assessment of Fretting Wear in Steam Generator Tubes Under Flow Induced Vibrations,” Flow-Induced Vibration, M.Pettigrew, ed., ASME, pp. 117–126, Paper No. PVP2003-2081, ASME Conference on Flow Induced Vibration; ASME PVP: Cleveland.
Mohany, A., Janzen, V., Feenstra, P., and King, S., 2012, “Experimental and Numerical Characterization of Flow-Induced Vibration of Multi-Span U-Tubes,” ASME J. Pressure Vessel Technol., 134, p. 011301. [CrossRef]

Figures

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Fig. 1

Velocity distribution in the U-bend region for the central plane of a CANDU steam generator at 100% power [23]

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Fig. 2

Flow cell concept for the fluidelastic instability model

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Fig. 3

Tube-support model

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Fig. 4

U-bend flow cell model

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Fig. 5

Crossflow velocity distribution along a typical steam generator U-bend tube (extracted from Fig. 1)

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Fig. 6

Mode shapes: (a) first in-plane mode (4.2 Hz), (b) second in-plane mode (10.4 Hz), (c) third in-plane mode (19.9 Hz), (d) first out-of-plane mode (58.1 Hz), (e) second out-of-plane mode (89.1 Hz), (f) third out-of-plane mode (96.4 Hz)

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Fig. 7

Linear tube response

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Fig. 8

Tube response for a clearance of 0.2 mm at various velocity ratios: normal impact forces at FBS 5 (a) 0.3, (d) 1.7, (g) 2.3; lift response spectra (b) 0.3, (e) 1.7, (f) 2.3; drag response spectra (c) 0.3, (f) 1.7, (i) 2.3

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Fig. 9

Effect of the radial support clearance (Cr) on the tube response for a support axial offset of Ca = 20 mm: (a) rms lift response, (b) rms impact force, (c) normal work rate

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Fig. 10

Effect of the support axial offset (Ca on the tube response for a radial clearance Cr = 0.01 mm: (a) rms lift response, (b) rms impact force, (c) normal work rate

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Fig. 11

Clearance distribution at the supports

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Fig. 12

Effect of the radial support clearance (Cr) on the impact force: (a) effect of Cr2 on impact at support 2, (b) effect of Cr7 on impact at support 7, (c) effect of Cr15 on impact at support 16, (d) effect of Cr9 on impact at support 10

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Fig. 13

Work rate histogram: (a) support 7, (b) support 8, (c) support 9, (d) support 10

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