EFFECTS OF PARTIAL INLET BLOCKAGES ON HIGH-VELOCITY FLOW-THROUGH A THIN RECTANGULAR DUCT - EXPERIMENTAL AND ANALYTICAL RESULTS

The Advanced Neutron Source (ANS) reactor was designed to provide a re search tool with capabilities beyond those of any existing reactors. O ne portion of its its state-of-the-art design required high velocity f luid flow through narrow channels between the fuel plates in the core, Experience with previous reactors had shown that fuel plate damage co uld occur if debris became lodged at the entrance to these channels. S uch debris disrupts the fluid flow to the plate surfaces and could pre vent adequate cooling of the fuel. Preliminary ANS designs addressed t his issue by providing an unheated entrance length for each fuel plate so that any flow disruption would have time to recover before reachin g the heated portions of-the fuel plates further downstream. As part o f the safety analysis, the adequacy of this unheated entrance length w as assessed using both analytical models and experimental measurements . The Flow Blockage Test Facility (FBTF) was designed and built to con duct experiments in an environment closely matching the ANS channel ge ometry. The FBTF permitted careful measurements of both hear transfer and hydraulic parameters. In addition to these experimental efforts, a thin rectangular channel was modeled using the FLUENT computational f luid dynamics computer code. The numerical results were compared to th e experimental data to benchmark the hydrodynamics of the model. After this comparison, the model was extended to include those elements of the safety analysis difficult to measure experimentally. These element s included the high wall heat flux pattern and variable fluid properti es.