Research On The Chaotic Mixing Characteristics Inside The Stirred Tank Of The Twin-blade Planetary Mixer

The solid propellant is one of the polymer based composite energy materials,and its production processes include the premixing,the mixing,and the pouring.Acting as the important power supply source of the solid rocket motor,the solid propellant plays an important role in the technosphere of the missile,the aviation and the spaceflight.The twin-blade planetary mixer,of which the mixing performance directly affecting the property and the safety during the solid propellant industrial processes,is the essential mixing equipment in the formula development and the batch production process for the solid propellant.The blades are the critical component of the twin-blade planetary mixer,because the kneading and stirring action of blades directly affect the mixing quality,the mixing efficiency and the mixing process safety.The chaotic mixing process of the twin-blade planetary mixer refers to some key problems,such as the mixing efficiency,the mixing power consumption,and the coupling action between the blades and the mixing material flow field.Centring on the key problems during the twin-blade planetary mixer chaotic mixing process inside the stirred tank,this dissertation selects the twin-blade planetary mixer of which the mixing volume being 1 L as the research object to systematically investigate the blade mixing mechanism,the blade torque load characterisics,and the blade deformation characteristics.The main research content is as following:Firstly,the chaotic mixing mechanism inside the stirred tank of the twin-blade planetary mixer is revealed.According to the Hamilton'sequations,combined with the chaotic mixing theory,the mapping relation is established between the fluid flow inside the stirred tank of the mixer and the Smale horseshoe.The blade installation site and the characteristics of blade tip movement rate are studied,and the mixing mechanism of the blade acting on the different components of mixing materials are analyzed.Through judging the distributing characteristics of the material granule inside the Poincare section,the chaotic mixing characteristics of the twin-blade planetary mixer are elaborated.And through analyzing the mixing index and the average strain rate of mixing materials,the material flow state and the mixing mechanism of the blade acting on the mixing materials are further revealed.Secondly,the influence relation of blade-structure parameters and technological parameters of the twin-blade planetary mixer on the chaotic mixing homogeneity is revealed.Known from the chaotic mixing mechanism of the twin-blade planetary mixer blades,the blade-structure parameters and the technological parameters directly affect the intensity of the shear,fold and stretch of the blade acting on the mixing materials inside the stirred tank.According to the definition of the Poincare section,utilizing the principle of statistics,the quantitative index of the material granule mixing uniformity inside the stirred tank is adopted and the mixing efficiency is quantitatively analyzed.At the same time,the influence relation of the blade-blade clearance,the helical angle and the rotating mode on the material granule mixing uniformity inside the stirred tank is studied,the key influence factors on the mixing efficiency of the twin-blade planetary mixer of which the mixing volume being 1 L are illuminated,and the blade-structure parameters and the technological parameters are further optimized.Thirdly,the change law of the blade's torque load is illuminated during the twin-blade planetary mixer chaotic mixing process.Based on the shearing,folding and stretching action during the chaotic mixing process of the mixer,the change law of the blade's instantaneous torque consumption and the relationship between the relative position of blades are revealed.The blade's instantaneous torque and the average torque are selected as the quantitative index of the blade's torque load to investigate the influence relation of the blade-structure parameters(blade-blade clearance,helicanl angle,and blade combined mode)and the technological parameters(blade rotating mode,blade rotation speed)on the characteristics of blade's torque load of the twin-blade planetary mixer.The change law of blade-structure parameters and the technological parameters on the blade torque consumption is revealed,and the key influence factors on the blade's torque consumption of twin-blade planetary mixer are illuminated.These can provide the theoretical basis for reducing the power consumption and power amplifier design for the mixer.Finally,the design criteria for improving the blade-structure stiffness of the twin-blade planetary mixer is provided.Based on the multi-field coupling action between the blade and the mixing material during the chaotic mixing process,the blade maximum deformation is selected as the quantitative index for the blade's deformation to investigate the influence relationship of the Newtonian fluid physical parameters(density,viscosity),the blade-structure parameters(blade-blade clearance,helical angle,blade combined mode),and the technological parameters(blade rotating mode,blade rotating speed)on the blade's maximum deformation.The safety of the blade's deformation is assessed.The key physical parameters of mixing materials affecting on the blade's deformation are revealed.The design criteria for decreasing the blade's deformation via increasing the blade's rigidity is put forward.And the mathematic relation between the technological parameters and the blade's deformation is established.The research results of this dissertation have important guiding significance for provding efficient mixing equipment,reducing production cost,and ensuring the industrial mixing process safety for the solid propellant.