Experimental observations of turbulent flow through subchannels of rod bundles

Abstract Experimental data on the structure of turbulence for longitudinal flow through rod bundles is required to validate computer codes predicting the detailed velocity and temperature distributions in rod bundles. Such codes are under active development. Experiments have been performed for a number of different geometries for turbulent flow through the wall subchannels of rod bundles. Detailed experimental results have been obtained of time-mean velocities, wall shear stresses, and the full Reynolds stress tensor by hot-wire measurements. Typical distributions of the axial turbulence intensity, the turbulence intensity parallel to the walls, and the kinetic energy of turbulence are presented. The experimental results show that the structure of turbulence in rod bundles differs greatly from that in circular tubes. The main features of this departure and the systematic trends observed are outlined. It is important for code developers to take into account the new experimental results in order to be able to predict temperature and velocity distributions in rod bundles with reasonable accuracy.