Numerical And Experimental Investigation On Liquid Film Flow Characteristics On Inclined Plate

Liquid film has high heat flux and high heat transfer coefficient at low flow rate.At present,liquid film flow has been applied to passive containment cooling system(PCCS)of advanced nuclear power plants.When a serious accident occurs in the reactor,the liquid film flow behavior and characteristics will affect the cooling capacity of the PCCS,which is directly related to the integrity and safety of the reactor.Therefore,it is of vital importance to study the liquid membrane flow behavior and its characteristics.In this paper,based on the diffuse-interface method,the two-dimensional numerical simulation of the liquid film flow behavior on the inclined plate is carried out,and the experimental guidance is given.The experimental study of the flow behavior of the liquid film on the inclined plate is carried out by using laser-induced fluorescence(LIF)technology.Based on the experimental data,a more reliable experimental relationship of the liquid film flow is obtained.The main work includes the following:In order to study the flow behavior of the liquid film on inclined plate,two-dimensional numerical simulation of liquid film flow behavior on inclined plate is carried out.Based on the diffuse-interface method,the whole process of liquid film flow on inclined plate from initial stage to full developed stage is simulated,and the maximum thickness and wave velocity of liquid film at different Reynolds numbers are obtained.Compare with the existing foreign experimental data to verify the reliability of the diffuse-interface method in simulating the liquid film flow on the inclined plate and the validity of the model.At the same time,the above methods and models are used to study and analyze the fluctuation state,wettability,flow rate and thickness of liquid film flow under the conditions of different plate inclined angle,contact angle,liquid surface tension and liquid density.It is found that the solitary wave phenomenon exist in liquid film flow.When the plate inclined angle and contact angle increase,the wettability of liquid film flow becomes worse.When the surface tension becomes smaller or the liquid density increases,the wetting effect of the liquid film can be improved.In order to study the flow behavior of the liquid film on inclined plate,the experiment of liquid film flow behavior on inclined plate is carried out.Based on the study of liquid film flow characteristics at home and abroad and the above numerical simulation,it is considered that the liquid film thickness is an important parameter in liquid film flow.Design and build an experimental platform for studying the liquid film flow behavior and characteristics on inclined flat plate using laser-induced-fluorescence(LIF)technology to make non-contact measurement of liquid film flow.By analyzing the statistical law of film thickness in the process of liquid film flow,the thickness and fluctuation of liquid film flow in different segments are studied.And the experimental correlation between the dimensionless film thickness and Reynolds number is obtained,and the image of the flow structure of the liquid film in three-dimensional space is reconstructed.