Study On Continuous Mixing Technology And Its Mechanism Of Solid Propellant Simulation Slurry Dominated By Elongational Deformation

The development of solid propellant mixing technology is limited by the solid content in solid propellant.The higher the solid content,the greater the energy and the higher the specific impulse of propellant.Normally,the high solid content makes the solid propellant slurry viscosity large,difficult to disperse,shear heat generation obvious and processing difficult,which furtherly limits the development of solid propellant to high energy.Most of traditional solid propellant mixing processes are mainly dis-continuous approaches,which has disadvantages of low production efficiency,long mixing time and high safety risk,and cannot meet the requirements of massive production of solid propellant with high solid content.In contrast,the continuous mixing of solid propellant based on twin-screw extruders show advantages of flexibility,continuity,high efficiency and low cost.However,due to the shear deformation dominated processing mechanism of twin-screw extruders,they have disadvantages of poor mixing and dispersion effect and large shear heat generation,which leads to potential danger issues during mixing and is also not conducive to the production of solid propellant with high solid content.The novel polymer processing theory proposed by Professor Qu Jinping,which is dominated by volume elongational deformation,has reversed the primary and secondary relationship between shear and elongational deformation,has advantages of high mass and heat transfer efficiency,good mixing and dispersion effect,short thermomechanical process,low shear heat generation,etc.If applied to the production of solid propellant slurry,it can effectively solve the problems of large shear heat generation and poor dispersion effect in current art.In this thesis,the volume elongational plasticizing transport technology is firstly applied to the mixing process of solid propellant,as well as the theory and method of continuous mixing of solid propellant controlled by volume elongational deformation are proposed.Thus,the volume elongational deformation dominated continuous mixing equipment of solid propellant is developed.The continuous and efficient mixing of solid propellant simulation slurry dominated by volume elongational deformation is successfully realized.Based on the reasonable assumption,the physical and mathematical models of solid propellant slurry mixed and transported in the biaxial eccentric rotor plasticizing transportation system are established.It is proved theoretically that the mixing and transportation of solid propellant slurry in this biaxial eccentric rotor plasticizing transportation system is dominated by elongational deformation.The influence mechanism of rotor speed and slurry solid content on the elongational deformation effect is revealed for the first time,which provides theoretical guidance and basis for actual production.The theoretical model of solid propellant slurry controlled by volume elongational deformation in the process of mixing and transportation is verified by means of experimental research.The influence of rotor speed and slurry solid content on the transport characteristics of biaxial eccentric rotor extruder and the performance of solid propellant simulated slurry mixture is explored.The feasibility of continuous mixing technology of solid propellant simulation slurry controlled by volume elongational deformation is verified,and the appropriate process parameters are obtained.The results show that the density uniformity of slurry mixture produced by the self-developed solid propellant continuous mixing equipment is excellent.Its output,energy consumption,transport efficiency,slurry temperature rise and online mixture amount are positively correlated with rotor speed and slurry solid content,while the residence time is negatively correlated with them.Specifically,when the solid content of the slurry is 86%and the rotating speed of the rotor is 120 r/min,the energy consumption per unit of the slurry is as low as 0.04 kw·h/kg,the residence time is only 70 s,the conveying efficiency is as high as99.06%,while the temperature rise of the slurry is only 2?,the online mixing amount is only0.837 kg,the density fluctuation value of the slurry mixture is as low as 0.021 g/cm~3,the standard deviation of the density is less than 0.007 g/cm~3,and the solid powder grading is still maintain good concrete gradation relationship.Therefore,it is believed the continuous mixing equipment of solid propellant dominated by volume elongational deformation can exhibit advantages of high output,low energy consumption,short residence time,high conveying efficiency,low temperature rise,small amount of online mixture and good mixing and dispersion effect,etc.The successful development of solid propellant continuous mixing equipment dominated by volume elongational deformation can realize the low energy consumption,continuous and efficient extrusion of high solid content solid propellant simulation slurry mixture.The resultant slurry mixture shows a good mixing and dispersion effect and density uniformity,which lays a good foundation for the continuous and safe production of high solid content solid propellant and has great practical significance to promote the development of China's aerospace industry.