Spectral measurements and mixing correlation in simulated rod bundle subchannels

Measurements of frequencies and spatial correlations of coherent structures in rod bundle flows

“…The decrease in pulsation frequency with diminishing gap size appears to contradict conclusions in previous literature on this topic (Möller, 1991;Wu and Trupp, 1994). However, closer examination of past experiments in which only a single rod was displaced towards a wall in ranges of W/D that were comparable to the present one (Wu and Trupp, 1994;Guellouz and Tavoularis, 2000a) shows a consistent trend of decreasing frequency as the gap diminishes.…”

“…However, closer examination of past experiments in which only a single rod was displaced towards a wall in ranges of W/D that were comparable to the present one (Wu and Trupp, 1994;Guellouz and Tavoularis, 2000a) shows a consistent trend of decreasing frequency as the gap diminishes. A detailed discussion of this topic will be presented in a future report, but all available evidence supports the conclusion that the pulsation frequency depends primarily on the geometry of the duct and to a secondary degree on the gap size.…”

“…In some cases, such as the CANDU reactor, a number of rod bundles in tandem are contained within a pressure tube. Several experimental studies have examined heat and momentum transport in rod bundles, particularly near the narrow gaps between rods and between rods and the surrounding duct, with the general conclusion that flow in these regions is dominated by quasi-periodic transverse flow pulsations (Möller, 1991;Rehme, 1992;Krauss and Meyer, 1998;Wu and Trupp, 1994;Wu, 1995;Guellouz and Tavoularis, 2000a,b;Chang and Tavoularis, 2005). It has been accepted that these flow pulsations are caused by large-scale vortices, which form in pairs on either side of each gap.…”

Thermal mixing between subchannels: measurement method and applications

“…Different empirical models have been proposed to predict the turbulent mixing with good success in regular geometries (Kim and Park, 1998). Nevertheless, the application of these models to non-regular geometries with gaps facing two subchannels of different shape, as is the case in wall subchannels or CANDU fuel bundles, is an area where further study must be done (Wu and Trupp, 1994).…”

“…Hot Wire Anemometry). These two methods have been widely used in the study of flows past rod-bundles (some examples are the works of Hooper, 1980;Hooper and Rehme, 1984;Renksizbulut and Hadaller, 1986;Wu and Trupp, 1994), giving local information about velocities and turbulence components. Thermal anemometry usually involves the use of large test sections due to the relatively large size of the probes.…”