The effect of inlet blockage configuration on flow behavior in rectangular channels

Experience with previous reactors has shown that inadequate cooling caused by partially blocked coolant channels can lead to fuel damage. This danger was of particular interest in the design of the Advanced Neutron Source (ANS) reactor. Preliminary designs addressed the issue of potential flow blockages by providing an unheated entrance length over which the flow disturbances would adequately recover. The Flow Blockage Test Facility (FBTF) was designed and built to conduct experiments in an environment closely matching the ANS channel geometry. In previous work the adequacy of this unheated entrance length was evaluated by testing various blockage widths at the edge and center of the channel entrance. This thesis is an extension of the initial study into the effect of blockage shape and position on downstream flow behavior. A series of non-standard blockage shapes and positions were designed, fabricated, and tested in the FBTF where flow field measurements were made using a Laser Doppler Velocimeter. Comparisons were made to corresponding standard square blockages to determine what effect, if any, a particular shape or position would have on downstream fluid flow. Using the computational fluid dynamics code Fluent, one blockage configuration was modeled and the use of various turbulence models and near wall treatments evaluated.