Measurements and Code Comparisons for Advanced Gas Reactor Coolant Channels Containing Spacer Ribs

Core coolant channels and control rod passages in prismatic gas-cooled nuclear reactors consist of typically hexagonal arrays of circular tubes or annuli containing spacer ribs. A major goal of an ongoing study to characterize the fundamental thermal fluid physics of high temperature flows in gas cooled reactors is to guide code development and assess code capabilities for treating forced convection problems in advanced reactors. Flow through an idealized annular channel containing an array of spacer ribs is examined both experimentally and computationally without complicating thermal phenomena. Laser Dopler Velocimetry (LDV) measurements in a transparent quartz model with index-matching oil flow are obtained in the INEEL’s unique large Matched Index of Refraction (MIR) flow facility to determine the velocity and turbulence fields, and to provide visualization of the flow. Experimental results are compared with numerical computations as a first step to understanding heat transfer enhancement and hindrance by the bluff spacer rib bodies.