Random Hydrodynamic Loads and the Vibration of Fuel Elements in the Turbulent Coolant Flow in WWER Fuel Assembly
Annotation on the basis of the multimeterings of pressure fluctuations on the perimeter of the fuel elements beam of the of full-scale mock-up fuel assembly WWER-440 of the second generation are obtained the realizations of the random hydrodynamic loads, which cause the vibrations of beam. It is established that in the region of initial hydrodynamic section near the lower supporting lattice. essential influence on the random hydrodynamic loads render the hydrodynamic conditions for shaping of the structure of flow at the entrance. Choke washers create the vortex structure of flow with the high levels of pulsating energy, which leads to the high intensities of vibrations in the initial hydrodynamic section. In the region of steady flow the levels of random hydrodynamic loads are reduced and to a lesser degree they depend on hydrodynamic entrance conditions. The generalizing empirical dependence of vibration movements on the random hydrodynamic loads are obtained. Two characteristic regions of the influence of random hydrodynamic loads on the vibration movements are discovered. With the values of random hydrodynamic loads of more than 80 N/m is observed a considerable increase in the intensity of vibrations, which is explained by the slippage of fuel element in the cell of the spacing lattice.