双基发射药螺杆挤压成型过程的模拟分析

Simulation Analysis of Screw Extrusion Process of Double Base Propellant

通过CFD仿真技术,应用MRF和滑移网格模型对双基发射药螺杆挤压成型过程进行数值模拟。由于塑化后的发射药属于假塑性流体,模拟中通过UDF引入发射药表观黏度系数的实验数据,采用层流模型模拟得到了发射药在螺杆挤压装置内瞬态和时均的流场信息。模拟结果分析显示,采用文中设计的螺杆结构,在设计工况下挤压孔口流速分布均匀,其值随时间变化幅度较小,可以保证双基发射药稳定地挤压成型,成型截面较为规则。运行中螺杆根部存在负压区对螺杆的功耗和振动都会有一定影响,可以通过调整料斗位置和料斗内螺旋导板的旋向加以改善。螺杆表面受力以压力为主,静压强的最大值比表面切应力大了2个数量级。

In this paper,making use of CFD simulation technology,MRF and sliding grid model to simulate the extrusion process of double base propellant screw was implemented.Since the plasticized propellant belongs to pseudoplastic fluid,the experimental data of apparent viscosity coefficient of propellant was introduced into the simulation through UDF,and the transient and uniform flow field information of propellant in the screw extrusion device was obtained by laminar flow model simulation.The analysis of simulation results shows that,the flow velocity distribution at the extrusion orifice is uniform under the designed working condition where the screw structure designed in this paper was adopted,and the change range with time is small,which can ensure that the double base propellant can be extruded stably and the molding section is relatively regular.There is a negative pressure zone at the root of the screw during operation,which has a certain impact on the power consumption and vibration of the screw.It can be improved by adjusting the position of the hopper and the rotation direction of the spiral guide plate in the hopper.The stress on the screw surface is mainly pressure,and the maximum value of static pressure is 2 orders of magnitude larger than the surface shear stress.