Experimental Measurements of Local Axial Gas Velocity and Void Fraction in Simulated PWR Steam-Generator Rod Bundles

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A dual spherical tipped optical fiber probe is used to obtain new data on local axial gas velocity and void fraction in a 4 × 3 rod bundle simulating a PWR steam generator. The average volumetric fluxes used were Jg = 1.52 - 2.44 m/s and J, = 0.47 - 0.68 m/s. Significant variations of Vg and α were found to exist downstream from the support plate. However the α range did not show any significant change between the flow holes and that downstream position, while Vg showed a more substantial variation. Values of Vg and α were very different between locations in the clearance gap around the tubes and that in the main flow holes. The gas flow rate was estimated to be only between 1–2.0% of that in the flow holes which could explain in part the existence of deposits in the clearance gap, due to decreased liquid velocity, leading eventually to tube denting in a PWR application.


Gas flow; Optical fiber probe; Pressurized water reactors; Probes (Electronic instruments); Rod bundles; Steam-boilers; Steam generator voids: Two-phase flow


Acoustics, Dynamics, and Controls | Aerodynamics and Fluid Mechanics | Aerospace Engineering | Mechanical Engineering | Nuclear Engineering


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