High Resolution Transverse Plane PIV Measurements of a 61-Pin Wire-Wrapped Fuel Bundle
Abstract: Liquid metal coolant reactors utilize a tightly packed triangular lattice of fuel pins wrapped with a helical wire spacer, enclosed in a hexagonal duct. The characterization of velocity fields inside of the fuel bundles is essential to the understanding and prediction of flow-induced vibrations (FIV) and temperature distributions in the field of thermal hydraulic research. Predictive computational tools based on modeling methods and computational fluid dynamics (CFD) are being researched and developed to accomplish this. However, a necessary step in the process of model development is validation with experimental measurements. The existing experimental velocity field data of these fuel assemblies are not suitable for CFD validation. The previous data was taken either with intrusive probes, lack spatiotemporal resolution, or utilized fuel bundles with insufficient pin counts which suggests wall effects had impacted behavior of subchannel flow of centeral subchannels. Lack of suitable data has created a demand for experimental data to be collected non-intrusively with high spatiotemporal resolution on the fuel bundle. An isothermal experimental flow facility was designed and constructed by Texas A&M University to produce experimental data of this caliber. This newest effort was to observe two-dimensional two-component (2D2C) PIV results on a transverse plane perpendicular to the axial flow of an average Re of approximately 14,250 in the turbulent flow regime. This plane contains exterior, corner, and interior subchannel types in LMFBR fuel bundles. Imaging of this plane required a proprietary design of a telecentric lens system to eliminate the effect of parallax when looking down a subchannel. Flow statistics such as ensemble-averaged velocity, RMS fluctuating velocity, and Reynolds shear stress have been calculated and contours of the quantities were plotted to discuss flow behavior in the corner, exterior, and interior subchannels to further understand the phenomena in these subchannels.
Nolan Goth*, Lance L.A. White, D.T. Nguyen, Rodolfo Vaghetto, and Yassin A. Hassan
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