Mapping of the Lateral Flow Field in Typical Subchannels of a Support Grid With Vanes

Abstract

Lateral flow fields in four subchannels of a model rod bundle fuel assembly are experimentally measured using particle image velocimetry. Vanes (split-vane pairs) are located on the downstream edge of the support grids in the rod bundle fuel assembly and generate swirling flow. Measurements are acquired at a nominal Reynolds number of 28,000 and for seven streamwise locations ranging from 1.4 to 17.0 hydraulic diameters downstream of the grid. The streamwise development of the lateral flow field is divided into two regions based on the lateral flow structure. In Region I, multiple vortices are present in the flow field and vortex interactions occur. Either a single circular vortex or a hairpin shaped flow structure is formed in Region II. Lateral kinetic energy, maximum lateral velocity, centroid of vorticity, radial profiles of azimuthal velocity, and angular momentum are employed as measures of the streamwise development of the lateral flow field. The particle image velocimetry measurements of the present study are compared with laser Doppler velocimetry measurements taken for the identical support grids and flow condition.

CFD methodology and validation for single-phase flow in PWR fuel assemblies

“…However, further downstream XCFD4NRS -Experiments and CFD Codes Application to Nuclear Reactor Safety OECD/NEA & IAEA Workshop Grenoble, France, 10 -12 September 2008 of the grid and approaching the next grid, the overall vane pattern and lateral boundary conditions have an important effect on the flow within a subchannel. This is seen in the test data (McClusky, 2003). Fortunately, the computing speed of computers and CFD solvers has improved dramatically over the last 10 years.…”

Numerical investigation and modeling of two-phase flow sweeping in rod bundles with mixing vane grid spacers

“…The decay of the angular momentum was compared with a Lamb-Oseen-Vortex. In a subsequent investigation, performed by McClusky et al (2003), with a different grid, a different vortical structure was found. Two co-rotating vortices were shed from the mixing vane tips which later merged into one vortex.…”

“…Holloway et al (2004) investigated the influence of mixing vane grids on the heat transfer. The same bundle as used by McClusky et al (2003) was used, but with 8 different grid spacers. It was found that the grid spacers can increase the heat transfer due to an increase of turbulence intensity.…”

Swirling performance of flow-driven rotating mixing vane toward critical heat flux enhancement

“…The studies [1,2] focused on each subchannel's characteristics, so swirl generation effect on neighborhood could not be predicted. In addition, the papers [3,4] did not provide swirl generation of the spacer grids.…”

“…Lateral velocity, axial vorticity, angular momentum, and azimuthal velocity profiles were discussed in a single subchannel. Additional work was conducted in the same experimental facility by comparing four subchannels in the assembly [2]. The PIV results were compared to the laser doppler velocimetry (LDV) measurement to provide the accuracy of the experiment.…”