Analysis of HDR blowdown experiment for fluid-structure interactions with multiflex

The HDR experimental facility of Kahlsruhe is comprised of a full-scale pressure vessel, core barrel, and piping systems. In the blowdown experiment, V31.1, the fluid-structure interaction of the core barrel and downcomer water is significant. This experiment is analyzed in the present paper. The HDR downcomer annulus is modeled by the one-dimensional network that is equivalent to two-dimensional fluid-structure interactions. The core barrel is modeled by the projector method for combined beam and shell models. The vessel motion is taken into account by means of the relative modal analysis proposed in this paper. Computed time histories of pressure, pressure differentials, and barrel wall displacements are compared with the experimental data. Fair agreement between experiment and post-test computation is found. Effects of the vessel motion are also discussed.