考虑壁面滑移修正的硝基胍发射药流道内数值模拟

壁面滑移是影响发射药压伸成型质量的重要因素之一。为了提高七孔硝基胍发射药压伸成型数值仿真的精确度,研究了发射药药料壁面滑移机理,建立了考虑壁面滑移修正的发射药流动的数学模型。采用有限元方法对七孔硝基胍发射药压伸成型工艺进行了数值模拟。对壁面考虑滑移与未考虑滑移时发射药流道内的压力场,速度场,收缩段与成型段交界处速度矢量分布情况进行了对比分析。通过发射药压伸试验进行了仿真验证。结果表明,壁面滑移降低了发射药成型压力,提高了发射药出口速率的均匀性,有利于发射药压伸成型。发射药实际尺寸与仿真尺寸误差均小于2.0%,其中,外径尺寸误差为0.59%,外弧误差为0.36%,内弧误差为1.80%,孔径误差为1.67%,中心孔径误差为1.72%,仿真工艺符合实际加工。

Numerical Simulation of Nitroguanidine Gun Propellant in Channel Considering Wall Slip Correction

The wall slip is one of the important factors affecting the quality of gun propellant extrusion molding. To improve the accuracy of numerical simulation of the seven-hole nitroguanidine gun propellant extrusion molding, the wall slip mechanism of nitroguanidine gun propellant dough was studied, the mathematical model of gun propellant flow considering the wall slip correction was established. The finite element method was used to simulate the forming process of seven-hore nitroguanidine gun propellant. The pressure field, the velocity field and the velocity vector distribution at the junction of the segment and the forming section were compared and analyzed at cases whether considering the wall slip. The simulation was validated by the gun propellant extrusion test. Results show that the wall slip reduces the forming pressure of gun propellant and improves the uniformity of gun propellant exit rate, which is beneficial to the forming of gun propellant. The error between the actual size and the simulation size of the gun propellant is less than 2.0% in which, the outer diameter error is 0.59%, and the outer arc error 0.36%, the inner arc error 1.80%, the aperture error 1.67%, and the center aperture error 1.72%. The simulation process is in line with the actual processing.