Study On Kinetic Characteristics Of Interaction Between Low Melting Point Molten Metal Droplet/column And Water

With the rapid development of modern industry,the demand for metallurgy and nuclear power has increased rapidly.However,during the metal smelting process and nuclear reactor operation,abnormal direct contact between the high temperature melt metal and the coolant may occur,resulting in a strong steam explosion.The interaction between the high-temperature melt metal and the coolant is a complex multi-phase flow phenomenon,especially the steam explosion,and moreover the mechanism of action still lacks a clear understanding,so it is still impossible to effectively prevent accidents and accurately assess production safety.In order to understand the mechanism of the interaction between the high-temperature melt metal and the coolant,an experimental facility is designed to reveal the physics of steam explosion.The high-speed camera technology was used to visualize the direct contact between metal droplet/liquid column and cooling water.The transient pressure measurement system was used to detect the pressure wave generated by steam explosion.Furthermore,the mechanism was discussed.The main conclusions of this paper are summarized as follows:The experimental study on the interaction between molten tin droplet and cooling water was carried out.First,four typical experimental phenomena(non-fragmentation,sheet expansion,sheet fragmentation and granular fragmentation)are found in experiment.Second,the phenomenon and the products are classified and counted.It is found that the increase of tin temperature promotes the vapor explosion of the droplet,which is shredded in the form of particles,and the increase of dropping speed promotes the droplet to be shredded in the form of sheets.Finally,based on the influence of tin temperature and drop height on the interaction,it is deduced that Kelvin-Helmholtz instability plays a dominant role in high-speed cases,while Rayleigh-Taylor instability plays a dominant role in lowspeed and high-temperature cases.The experimental study on the interaction between molten tin column and cooling water was carried out.First,it is found that the interaction between the tin liquid column and the cooling water can be divided into two stages namely involving falling phase and deposition phase.The severe steam explosion with great intensity may occur during the deposition phase.Secondly,in the tested temperature range in this paper,it is found that an increase in the tin temperature,or the diameter of the liquid column or imposing the protection of inert gas promotes the local steam explosion in the falling stage.On the contrary,an increase in the dropping height significantly inhibits the local steam explosion.For the deposition phase,an increase in the tin temperature,or dropping height or imposing the protection of inert gases increases the intensity of the steam explosion.The increase in the diameter of the liquid column also increases the intensity of the steam explosion.However,as the diameter is increased to 15 mm,the interaction is inhibited so that no severe steam explosion occurs.The experimental study on the interaction between molten aluminum and cooling water was carried out.It is found that in the tested range in this paper,the interaction between molten aluminum and cooling water is relatively flat,and neither the aluminum droplet nor the aluminum liquid column has obvious destructive behavior and steam explosion behavior.However,in an experiment with the aperture of 10 mm,the bottom sediment suddenly expanded,indicating that the steam explosion between the aluminum liquid column and the cooling water is possible.