【作者】 杨明金；

【导师】 杨叔子； 李锡文；

【作者基本信息】 华中科技大学 ， 机械制造及其自动化， 2008， 博士

【摘要】 固体推进剂药浆混合是固体推进剂生产的关键工序之一,药浆的混合性能直接影响推进剂的加工性能、力学性能和燃烧特性。混合是流体流动的特殊形式,在数学上表示为映射,由拉格朗日法或欧拉法描述。根据立式捏合机混合釜内流体动力学系统混合域几何结构的轴对称性,提出了混合釜内流场遍历率、混合率和混合时间等概念,分析了立式捏合机几何参数和运动参数对系统遍历性和混合性能的影响。通过引入穿越影响因子,定量地研究了穿越对系统混合性能的影响,揭示了系统遍历和系统混合是两个不同的过程,遍历过程中流场轨线速度方向的不断变化加速了混合进程。提出了根据Smale马蹄映射模型原理来构建流体混合动力学系统的方法,分析了立式捏合机几何参数和运动参数对系统混合率和混合时间的影响,结果表明,在一定几何参数和运动参数的条件下,存在螺旋桨自转公转转速比的最佳取值范围,使流体动力学系统表现出较强的混沌特征。在准静态流体动力学系统假设条件下,分析了单螺旋桨和双螺旋桨二维流体动力学系统流函数的分布特征,结果表明,双螺旋桨的异速转动使混合釜内流线形状发生一定变化,剪切速率为0的区域减小,能抑制规则岛的产生。采用动网格法通过用户自定义函数功能编写源程序并经编译和调用,实现了混合釜内网格随着螺旋桨的行星运动而自动更新。提出了将按固体推进剂药浆混合工艺操作达到一定混匀标准的固体推进剂药浆作为“连续相”的假设,通过离散相模型数值仿真分析了立式捏合机几何参数和运动参数对固体推进剂药浆固相组分运动历程的影响,揭示了固体推进剂药浆固相组分的运动规律。通过欧拉模型数值仿真分析了混合釜内固体推进剂药浆流体动力学系统的混沌特征,揭示了固体推进剂药浆在复杂混合域内的混合规律。提出了体积加强平均分离强度的概念,用于计算和分析固体推进剂药浆密度测量值与其均值的偏离程度,获得了固体推进剂药浆混合均匀性的评价。通过对固体推进剂药浆混合均匀性实验结果的极差分析和方差分析,得到了固体推进剂药浆混合工艺参数对药浆混合性能影响的显著性程度。更多还原

【Abstract】 Mixing process is one of the key processes for the production of solid propellants. The mixing performance of the solid propellant slurry directly affects machining properties, mechanical properties and combustion characteristics of the propellants. Mixing, expressed as mapping in mathematics, is a special form of fluid flowing, and it can be described by Lagrangian Method or Eulerian Method.According to the axial symmetry of geometry of the mixing domain of the fluid dynamics system in the mixing tank of a vertical kneader, definitions of Ergodicity Rate, Mixing Rate, Mixing Time, etc., were presented in the dissertation. The influences of parameters of geometry and kinematics of the kneader on ergodic and mixing performance of the system were analyzed. By introducing impact factor of crossing, the influences of crossing on the mixing performance were quantitatively studied, and results revealed that ergodicity and mixing are different processes of a system, of which, the continuous changes of velocity directions of the trajectory of the fluid in ergodic process accelerate the mixing process.A method of constructing fluid dynamics system of mixing based on Smale Horseshoe Mapping Model was put forward. The influences of parameters of geometry and kinematics of the kneader on Mixing Rate and Mixing Time of the system were analyzed. Results show that there is such an optimal range of speed ratio of rotation and revolution of the hollow blade for certain parameters of geometry and kinematics of the kneader that makes the fluid dynamics system hold strong chaotic properties. With assumption of fluid dynamics system being quasi-static, the characteristics of stream-function distributions of the two-dimensional systems of single screw blade and that of double screw blades were analyzed. Results show that double screw blades with different revolution speeds can make changes of the shapes of the trajectory in the mixing tank, and area of the zero shear rate region decreases as a result, which prohibits the generation of regular islands.By adopting Dynamic Mesh Model, mesh auto-updating with the planetary motion of the screw blades was realized after source code, based on User Defined Functions, being edited, compiled and hooked. Assume that the solid propellant slurry, which was prepared following the ordinary mixing process and reached some standard of mixing uniformity, is the continuous phase of a mixture of a fluid dynamics system, then the influences of parameters of geometry and kinematics of the kneader on the movement course of solid phase particles of the solid propellant slurry were analyzed by the use of Discrete Phase Model, and the movement characteristics of solid phase particles of the slurry was revealed. Moreover, the chaotic properties of the solid propellant sluny dynamics system in the mixing tank of the kneader was analyzed by the use of Eulerian Model, and the mixing mechanism of the solid propellant slurry in a complex mixing domain was revealed.Volume-weighted Intensity of Segregation was defined, and it was employed to compute and analyze the deviation of the tested density from the average value of the solid propellant slurry, then the evaluation of mixing uniformity of the slurry was obtained. Major parameters of the mixing process and their significant levels affecting the mixing performance of the slurry were also obtained by means of range analysis and variance analysis of the tested results of mixing uniformity of the solid propellant slurry.更多还原