Velocity Measurements in the Subchannel of the Wire-Spaced Subassembly

Measurements of the flow velocity and direction in wire-spaced rod bundles were performed in air flow with a 37-rod subassembly that consisted of rods 31.6 mm in diameter, 3464 mm long, 6.0 mm in spacer wire diameter, and 1100 mm in wire wrapping pitch. The fine flow velocity and its direction were measured in both interior and wall subchannels in two sections of axial direction. Circular flow and decrease of axial flow velocity were observed in the subchannel containing the spacer wire. The variation of the transverse flow rate within one spacing wire pitch, which occurred between two adjacent subchannels, was obtained from the measured value to develop the computer program for the subchannel analysis.