<p>Recent&nbsp;interest&nbsp;for&nbsp;the development of high-temperature gas reactors&nbsp;has&nbsp;increased the need for&nbsp;more advanced understanding of flow characteristics in randomly packed pebble beds.&nbsp;A proper understanding of these flow characteristics can provide a better idea of the cooling capabilities of the system in both normal operation and accident scenarios.&nbsp;In order to enhance the accuracy of fast,&nbsp;intermediate&nbsp;fidelity modeling,&nbsp;high-fidelity simulation may be used to generate correlative data. For this research,&nbsp;NekRS, a GPU-enabled&nbsp;spectral-element computational fluid dynamics code, was used in order to produce the high-fidelity flow data&nbsp;for beds of 1568 and 45,000 pebbles.&nbsp;Idaho National Lab’s Pronghorn porous media code was used as the&nbsp;intermediate&nbsp;fidelity code.&nbsp;The high-fidelity model was separated into multiple&nbsp;concentric&nbsp;regions in postprocessing in order to extract porosity and velocity averages in each region. The porosity values were input into the Pronghorn model and the resulting velocity profile was compared with that from&nbsp;NekRS.&nbsp;Both cases were run with a Reynolds number of 10,000.&nbsp;The&nbsp;Pronghorn results were found to significantly overestimate the velocity in the outermost region, so further work is to be done to investigate and improve this discrepancy&nbsp;and develop a more effective drag coefficient correlation for the near-wall region.&nbsp;</p>

Comparison of Pebble Bed Velocity Profiles Between High-Fidelity and Intermediate-Fidelity Codes

Paper Proceedings: https://asmedigitalcollection.asme.org/ICONE/ICONE28/volume/85246

2021 28th International Conference on Nuclear Engineering (ICONE28)

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