The Flow Field Study Of Drum Type Blender Based On CFD

The casing and flavoring are important procedures in the cigarette processing,the mixing performance quality directly impacts on the character change(such as the tobacco breakage percentage,temperature and humidity),the uniformity of the casing and flavoring and the use efficiency of flavor liquid during the procedure.The drum mixing is a dynamic process,which is not only affected by the roller structure,properties of liquid material but also the air movement,roller operating speed and the concentration of tobacco and other factors.The virtual prototype of the casing and flavoring drum is established in this thesis.The mixing properties and the multiphase flow field inside the blender drum are simulated by numerical simulation with CFD software-Fluent and the result is analyzed.The main works of numerical simulation are as follows:In this paper,gas flow field in the internal roller is briefly analyzed to verify the feasibility of pneumatic mixing.Effect with different locations of entry and exit vents to the air flow inside the drum is studied,which shows that entry and exit vents installed away from the center of the drum shaft produces strong swirling near the cylinder wall and are not conducive to the tobacco movement to the ideal formation.On the other hand,the ones lay next to the central axis of roller produces better swirl while form a large updraft at the bottom center of the cylinder,and are more conducive to the movement of tobacco.The DPM model was exploring used for the researches on flaky particles-air two-phase flow field.The shape factor was used to correct the calculation,and the orbit of the flaky particles in the air flow field was determined with double coupling,which is compared with the single coupled computing results.The influence on the tobacco particle movement track by different tobacco particle diameter and speed of the roller is studied which the accuracy of tobacco rotation characteristics with the model is further validated.In order to fully analysis and research the internal flow field of roller blender,the effect among the three phases(the spatial compressed air,liquid and tobacco)is considered.Numerical simulation of the three-phase internal flow field of roller blender is simulated by Euler/Euler/Lagrange mathematical model,whose results are basically capable of reflecting the three phase states flow in the apparatus.The influence of different operating parameters to the drum velocity field,concentration field,the entire region droplet trajectory and mass concentration is studied.The simulation result indicates that they have their own effect role to the mixing character of the drum.So,the proportion of all the parameter must be in a reasonable match if the drum will have a good mixing quality.