Propagation of Expansion Wave in Flexible-Wall Tube

Abstract

As a model of the fluid-structure interaction which occurs during the loss-of-coolant accident in pressurized water reactors, the pressure variation in the expansion wave propagating through the flexible-wall tube was measured along with the deformation of the wall. An analysis of the experimentally observed phenomena is performed by solving onedimensional flow equations coupled with an equation of the wall deformation. The method employed is a numerically stable semi-implicit donor-cell difference method.The rate of the pressure decrease was found to be reduced in comparison with the case of the rigid-wall tube. The fluid-structure interaction generates the pressure profile which is, apparently, regarded as a superposition of the pressure profile of the expansion wave in the rigid-wall tube and the disturbance which is generated by the deflection of the flexible wall. The vibrations of the pressure and the flexible wall due to the inertia of the wall were also found. Both the damping of the deflection and the wall friction of the structure are found to be important parameters pertinent to the fluid-structure interaction phenomena.