Mixing Performance Analysis And Structure Optimization Of A Double-shaft Paddle Mixer

Mixing machine is the key equipment in feed,chemical and other fields.the twin shaft paddle mixer because of its high mixing efficiency,good mixing effect has become one of the most widely used type of mixer.the researchers in this field has accumulated a large number of statistical data and experience,but the movement information of material within the mixing machine is poorly understood,the mixing characteristics and mixing mechanism is not clear.In this paper,the mixing mechanism,mixing characteristics and structural optimization of a twin shaft mixer arc numerically simulated,which not only has important guiding significance for the optimization design of the hybrid equipment,but also has practical theoretical significance for the development of new type of hybrid equipment.the main contents are as follows:(1)The modeling theory and technology of the mixing process of powder are studied.Based on the Solidworks,ICEM CFD and Fluent platform,the structure theory of turbulence model,multiphase flow model,mixed reaction model,dynamic region calculation model and mechanics model had been studied.Determined the suitable numerical model of powder double shaft paddle mixing.turbulence model uses Standard k—? Model.multiphase flow model uses Mixture Model.mixing reaction model uses Species Model,dynamic region calculation model uses Dynamic grid model.(2)Established a numerical model for the mixing process of a double shaft paddle mixer and carried out the numerical simulation of mixing characteristics.A finite element analysis model based on Fluent platform has been established,and the correctness of the model by mixing machine torque experiment also has been verified.Based on the model,By adding the tracer,studied the changes of different monitoring points and analysed the mixing rules in the mixer.Determined the mixing time calculation standard.The mixing uniformity,mixing power and unit volume mixing energy were calculated.(3)research on mixing characteristics of mixing machine under different working parameters.The influence of the shape of blade,blade angle,filling rate and rotor speed on the mixing characteristics was studied.Research shows that the wedge blade is better than the square blade;the blade installation angle in the shortest mixing time and mixing characteristics of the best;the increase of speed can greatly reduce the mixing time.At the same time,increase the torque is also very obvious;when the filling rate is less than 70%,increasing the filling rate of mixed time increased significantly,while more than 70%,the mixing time is basically unchanged,the filling rate should be higher than 70%.(4)The numerical simulation of the structure optimization of the mixer is studied.Two optimization schemes for installing small paddles on the brace and installing small paddles on the shaft are put forward.The research results show that installing small paddles on the brace can shorten the mixing time by 56.45%,reduce the mixing capacity of the unit volume by 56%,and improve the mixing homogeneity.