Experimental Investigation On Fluid-Structure Interaction Phenomena Caused By The Flow Through Double-Plate Structure In A Narrow Rectangular Channel

Compare with the fuel assemblies of PWR, parallel plate-type fuel assemblies were used in some advanced research reactors and military reactors as power producer due to its high power density and good heat transportation characteristic. Coolant flow through the sub-channel with high flow rates, which between two adjacent fuel plates, may induce severe fluid-structure interaction (FSI) phenomena between the flowing fluid and the plates. The phenomena could threaten to operation safety of nuclear reactors. Therefore, it is very important to do deep research on FSI vibration characteristics of parallel plate-type structure. In this paper, plate-type fuel assemblies were sampled into two-plate structure which is four-corner fixed in a rigid rectangular channel. Through the advanced measurement technology, the narrow-frequency and large-amplitude opposite-phase vibration, same-phase bend and irregular vibration were observed in specific flow rate ranges. Compared with the behaviors found in the single-plate structure FSI experiment, some differences and similarities were summarized. The main reasons for the differences were thought to be the additional mass and additional damping change sticking to the plates. The narrow-frequency and large-amplitude opposite-phase vibration was found before the Miller’s critical velocity is a new FSI mechanism, which could make the plate-type assemblies’ failure and damage. The same phase bend was also found firstly in specific flow rate range. The new finds will provide a theory basis and engineering guide, which could be a new guide for avoiding fluid-structure interaction problems of plate-type fuel assemblies in the nuclear reactors’design and operation.