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Multiphase Flows

Hydrodynamics of Jets From Guillotine Steam Generator Tube Rupture: Modeling, Analytical Results, Computational Fluid Dynamics Calculation, and Comparison With Experimental Data

[+] Author and Article Information
J. L. Muñoz-Cobo

Universitat Politécnica de Valencia,
Instituto de Ingeniería Energética,
Camino de Vera s/n,
Valencia 46022, Spain
e-mail: jlcobos@iqn.upv.es

L. E. Herranz

CIEMAT, Centro de Investigaciones Energéticas,
Avenida Complutense 22,
Madrid 28040, Spain
e-mail: luisen.herranz@ciemat.es

A. Escrivá

Universitat Politécnica de Valencia,
Instituto de Ingeniería Energética,
Camino de Vera s/n,
Valencia 46022, Spain
e-mail: aescriva@iqn.upv.es

Contributed by the Fluids Engineering Division of ASME for publication in the Journal of Fluids Engineering. Manuscript received June 5, 2012; final manuscript received September 28, 2012; published online November 20, 2012. Assoc. Editor: Francine Battaglia.

J. Fluids Eng 134(12), 121302 (Nov 20, 2012) (11 pages) doi:10.1115/1.4007804 History: Received June 05, 2012; Revised September 28, 2012

In this work we study the hydrodynamics of characteristic gas jets resulting from guillotine breaks of steam generator tube rupture sequences (SGTR) in pressurized nuclear power reactors. As an initial step towards describing an “in-bundle” gas jet, a hydrodynamic model of free gas jets emerging from a guillotine break under prototypical SGTR conditions has been developed. First we have studied the jet characteristic for an isolated tube; the analytical model estimates variables such as trajectories, centerline velocities, velocity distribution, and Reynolds stresses. We have performed model comparisons with experimental data for different experimental conditions with different mass flow rates, and we have found good agreement of the model with the experimental results. Additionally, an “ad hoc” expression has been derived for the centerline jet velocity, which has been experimentally confirmed. Consistently with the experimental data and the computational fluid dynamics (CFD) calculations the analytical model predicts no outflow near the jet center. As a complementary issue, we have performed CFD calculations for a guillotine tube rupture when the tube is surrounded by several rows of neighboring tubes, in this case the jet trajectories are affected by the Coanda effect near the tubes.

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References

Figures

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Fig. 1

Geometry of a jet from a steam generator tube rupture (SGTR); (a) is for an ideal free jet produced in a guillotine tube rupture with only velocity radial component, (b) is for a jet with initial velocity components in the radial and axial direction and forces that bend the jet

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Fig. 2

Normalized transversal velocity component to the jet axis versus ξ. The upper curve displays uz(r,z)/uc(r) versus ξ = z/δ(r) for the free radial jet from a SGTR with only radial component at the rupture. The lower curve (thinner line) displays the normalized velocity component uy(s,y)/uc(s) versus ξ = y/δ(s), for a curved jet with radial symmetry.

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Fig. 3

Normalized Reynolds stress versus ξ for the radial free jet with azimuthally symmetry

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Fig. 4

Natural curvilinear coordinates for a jet produced in a guillotine SGTR

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Fig. 5

Normalized Reynolds stress versus ξ for the curved jet with azimuthally symmetry (+) and the radial free jet with azimuthally symmetry denoted by the continuous line

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Fig. 6

(a) Experimental normalized mean velocity field for run number 2 of the free radial jet inside an enclosure; (b) guillotine TR break used in the experiments

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Fig. 7

(a) Jet trajectory z versus r for run 2. The 0 denotes the experimental points and the continuous line the fit to Eq. (24). (b) Jet trajectory, z versus r for run 3.

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Fig. 8

Experimental centerline velocities (o) for runs 2 and 3, displayed at (a) and (b), respectively. The red continuous lines give the prediction of the radial model of this paper while the blue dashed lines give the prediction of the planar model.

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Fig. 9

(a) Normalized velocity distribution in the jet direction at 60 mm from the rupture for run 75, using c1av=0.325. The experimental data are displayed in blue while the symmetric Gaussian points are displayed by green bubbles (o). (b) Normalized velocity distribution in the jet direction at 70 mm from the rupture for run 100, using c1av=0.270.

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Fig. 10

(a) and (b) Normalized velocity distribution in the jet direction at 60 mm and 70 mm, respectively, from the rupture for run 75, using c1+ = 0.345 and c1− = 0.306 for positive and negative values of y. The experimental data are displayed in blue while the asymmetric Gaussian points are displayed by green bubbles (o); the same spreading constants were used for both figures.

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Fig. 11

Enlarged central region of the jet for run 1 (Qair = 150 kg/hr); no outflow is observed in this region

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Fig. 12

Interaction of the jet with the neighbor tubes

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