Interfacial behaviors, kinetic analysis and dynamic parameters of disturbance waves in 3 × 3 rod bundle channels

Abstract

To facilitate operational monitoring and accident management in various nuclear power plants, it is essential to investigate the interfacial behaviors, parameter characteristics, and formation mechanisms of annular flow in rod bundle channels. A visual experimental system was developed to record and classify the interfacial behaviors of disturbance waves on side and corner rods. The results indicated that the disturbance waves can be categorized into Small-scale waves, Bag-crest waves, and Ligament-crest waves. The flow map of the two channels indicated that wave structures with lower heights in Channel-1 appeared earlier when the liquid phase velocity remained constant. The peak values in the Power Spectral Density (PSD) results reflect the type and energy of various waves. The highest peak value gradually increases as the wave structure transitions from SS, BC, LC to LC-ll waves. The increasing texture lines with the highest values in the RP results indicate a distinct periodicity of BC waves. Furthermore, the periodicity of BC waves is more pronounced on the corner rod than on the side rod. The MPE value increases as wave types change from Small-scale to Single-crest waves. Additionally, the value of liquid film thickness are generally higher than that of pressure drop. The wave height, velocity, and frequency under different flow conditions were presented and compared. The results indicated that variations in dynamic parameters are closely related to the characteristics of disturbance wave structures.