FIV2018 Paper Management System, FIV2018 Conference

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Transverse and Streamwise Fluidelastic Instability in Rotated Square Tube Arrays
Marwan Hassan, Dave Weaver

Last modified: 2018-04-21


The San Onofre Nuclear Generating Station (SONGS) was shut down after fluidelastic instability (FEI) produced numerous tube leaks through tube-to-tube impacting. Normally, this instability is expected to occur with tube motion in the direction transverse to the direction of flow. At SONGS, the instability occurred in the plane of the U-bend tubes, a phenomenon never before documented in a nuclear steam generator in service. The authors previously developed a simple theoretical model for streamwise FEI for parallel triangular tube arrays, the results compare well with existing experimental data. It was shown that streamwise FEI was very sensitive to array pitch ratio and mass damping parameter. In the present paper, that model is extended to the rotated square tube array. The results of comprehensive parametric studies are presented for the effects of pitch ratio, and mass damping parameter on the transverse and streamwise FEI in this array geometry. Computations were carried out for single flexible tubes in a rigid array and multiple flexible tube arrays for tube motion in the transverse and streamwise directions independently. Comparisons are made with existing experimental data. It is seen that array geometry has a significant effect on the tendency for streamwise instability and physical insights are developed to explain the observations.



Fluidelastic Instability, Streamwsie vibrations, Nuclear Steam Generators, tube arrays

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