压水堆密封旋转喷嘴出口附近区域液滴粒径和速度分布的实验测量

During the course of a hypothetical severe accident in a nuclear Pressurized Water Reactor (PWR), hydrogen may be produced by the reactor core oxidation and distributed into the containment. Spray systems are used in order to limit overpressure, to enhance the gas mixing to avoid hydrogen accumulation, and to wash out the fission products. In order to simulate these phenomena with CFD codes, it is first necessary to know the droplet size and velocity distributions close to the outlet nozzle. Furthermore, since most of the phenomena relative to droplets (condensation, gas entrainment, collision) are of particular importance in the region below the nozzle, accurate input data are needed for real-scale PWR calculations. The objective is therefore to determine experimentally these input data. Experimental measurements were performed on a single spray nozzle which is routinely used in many PWRs. This nozzle is generally used with water at a relative pressure supply of 350 kPa, producing a mass flow rate of approximately 1 kg/s. At a distance of 20 cm, where atomization is just achieved, it is found that geometric mean diameter varies from 305 to 366 μm, Sauter mean diameter from 430 to 600 μm and mean axial velocity from 14.1 to 18.4 m/s.