Experimental Investigation of the Enthalpy and Mass Flow Distribution in 16-Rod Clusters with BWR-PWR Geometries and Conditions

摘要

Enthalpy and mass flow distribution at the outlet of two test sections with uniform heating in axial and radial direction under steady state conditions was measured by simultaneous sampling of five of six characteristic subchannels in the bundle, using the isokinetic technique and analyzing the outlet quantities by a calorimetic method. Results show low steam quality for the corner subchannel under BWR conditions, due to a thick liquid film on the unheated channel wall. Experimental data confirm the usefullness of the subchannel sampling technique for understanding thermohydraulic phenomena under two-phase flow conditions in multirod bundles. Subchannel resistance coefficients for both types of spacers under one-phase flow conditions were calculated by a substructure method, showing a high local value of the corner subchannel. Total resistance of the spacer was evaluated using local drag coefficients. It agrees well with measured values under adiabatic conditions.