Numerical Simulation Of Flow And Heat Transfer Of Droplet Impact On Wall At Different Temperatures

Due to the high content of chloride ions in the tailings extracted from high titanium blast furnace slag of a certain plant through the process of "high temperature carbonization and low temperature boiling chlorination",it can be used only after the treatment of its high content of chloride ions.It is an important way to form superheated boiling co-efficient dachlorination reaction at the micro interface of the tailings by colliding with the tailings with fluidized water.In this paper,the flow characteristics of water droplet impact on the normal temperature surface,especially the spreading characteristics,and the flow characteristics and heat transfer characteristics of the droplet impacting on the high temperature surface were studied respectively.Firstly,the theory and method in the process of establishing the model of droplet impacting on the wall by Fluent were described.Then,the numerical simulation of the process of droplet impacting on the normal temperature wall and high temperature wall was carried out respectively.Based on the simulation of the droplet impact on the normal temperature wall,the droplet impact oscillation is divided into three stages,and by combineing the dynamics behavior of the droplet with the pressure field and the velocity field,it is verified that the process of the continuous transformation and consumption of the kinetic energy during the droplet spreading.On the basis of this,the influence of We number on the spreading characteristics of droplets was studied,and it was found that both droplet impact velocity and droplet diameter promoted the spreading.The difference was that the impact velocity promoted the spreading process more obviously,while the droplet diameter had a significant influence on the spreading results.With the increase of droplet impact velocity,the maximum spreading coefficient will have a peak value controlled by droplet diameter.At the same time,it is also found that the spreading coefficient of droplets is not the same or even different under the same We number condition,so it is not possible to use a single We number to quantify the spreading coefficient of droplet diameter.Finally,through the study of surface tension coefficient and contact Angle,it is found that the increase of both of them can inhibit the spreading,the difference is that the surface tension can not only inhibit the maximum spreading but also accelerate the speed of the whole spreading process.By simulating the impact of droplet on high-temperature surface,it is first studied that the situation which the temperature of the wall surface was 573 K,which verified three different dynamics behaviors of the droplet impact with the change of We number:unbroken,broken in retraction process and broken in spreading process.On this basis,through the wall temperature,droplet diameter and impact velocity on the spreading characteristics of the study,it is found that the influence of droplet diameter and impact velocity is consistent with the influence at normal temperature.The wall temperature has no significant effect on the spreading characteristics at the initial stage of impact.After the droplet temperature rises,the spreading coefficient will increase to a certain extent due to the change of droplet physical properties.The heat transfer characteristics were studied through the influences of droplet diameter,impact velocity and wall temperature on the wall heat flux.It was found that all the three factors would increase the maximum wall heat flux,and the influence of droplet diameter and wall temperature on the wall heat flux was greater than that of impact velocity.