Development of Swirling Flow in a Rod Bundle Subchannel

Abstract

Experimental measurements of the axial development of swirling flow in a rod bundle subchannel are presented. Swirling flow was introduced in the subchannel from a split vane pair located on the downstream edge of the support grid. Particle image velocimetry using an optical borescope yielded full-field lateral velocity data. Lateral flow fields and axial vorticity fields at axial locations ranging from 4.2 to 25.5 hydraulic diameters downstream of the support grid were examined for a Reynolds number of 2.8×104. The lateral velocity fields show that the swirling flow was initially centered in the subchannel. As the flow developed in the axial direction, the swirling flow migrated away from the center of the subchannel. Radial distributions of azimuthal velocity and circulation are presented relative to the centroid of vorticity, and are compared to that of a Lamb-Oseen vortex. The angular momentum decreased as the flow developed in the axial direction. The spatial decay rate of the angular momentum is compared to that of decaying, swirling flow in a pipe.

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

“…The model of McClusky et al (2002) was adopted in order to compute the lateral flow intensity for each sub-channel. The decay rate of the lateral flow intensity is not constant over the axial distance, especially in the non-interior sub-channels.…”

“…The region of influence was extended up to 20 hydraulic diameters downstream of the grid spacer. McClusky et al (2002) used the Particle Image Velocimetry (PIV) method for measurements of the velocity and vorticity of water flow in a 5 Â 5 rod bundle. It was shown that the mixing vanes induce a strong swirling flow.…”

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

“…To investigate the flow field downstream of mixing vanes, a testing methodology was developed to measure the lateral flow field at various elevations downstream of the grid. Particle Image Velocimetry is the technique used in this testing (McClusky, 2002). To investigate the average heat transfer coefficient, a testing methodology was developed to measure the heat transfer coefficient as a function of axial distance downstream of the grid (Holloway, 2004).…”

“…Particle Image Velocimetry (PIV) is the technique used. This technique is described in detail by McClusky (2002). PIV measurements require illumination of particles in the flow field (water at ambient conditions) using a laser, and image capture using an optical borescope attached to a camera that transmits the data to a computer for post-processing.…”

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

“…Particle image velocimetry (PIV) technique was utilized in a horizontal flow facility using a split vane [1]. The split vane was designed to form a 30°angle relative to the flow direction.…”