Variation of pressure load on flexible plate due to interaction between an expansion wave and the flexible plate

Abstract

The interaction between an expansion wave and a flexible plate was investigated as a model of the fluid-structure interaction which occurs during the loss-of-coolant accident in pressurized water reactors. The test section, which was connected to an expansion tube, was divided into two regions by the flexible dividing plate, and pressure variations in both regions were measured. Two-dimensional flow equations were numerically solved coupled with an equation of the deflection of the plate. The reduction of pressure loads on the plate due to the interaction between the plate and the expansion wave only occurred within the early stage when the pressure on the back side of the plate was constant. The pressure in the back-side region of the plate was based on the volume change in that region, and the net effect of the pressure change in that region was the reduction of the load on the plate. The pressure in the outlet-side region of the plate was not affected by the pressure in the back-side region. Pressure disturbances generated by the deflection of the dividing plate were found to propagate around the plate when the test section was not perfectly divided into two regions. It was concluded that the conditions around the structure (back-side volume of the structure, for example) should be considered in the evaluation of the pressure load on the structure when the fluid-structure interaction phenomena may be important.