Turbulence and rod vibrations in an annular region with upstream disturbances

Abstract

Disturbances in nominally parallel flow are produced by the use of grids upstream of a flexible rod in an annular region. The turbulence decay in two annular regions and the vibrations of the same rod are measured for a wide range of flow velocities, grid configurations, and hydraulic diameters typical of those found in nuclear reactors. The creation and characterization of the upstream flow disturbances as a test parameter are the unique contributions of the work. The data show that upstream turbulence propagated well into the annular region with the largest hydraulic diameter and had a significant effect on the rod vibration. However, for the smallest hydraulic diameter the upstream disturbances decayed very rapidly and the rod vibration was nearly identical for different upstream disturbances.