聚磷腈复合材料的烧蚀数值仿真

Ablation simulation of poly(diaryloxyphosphazene)composites

聚磷腈(PDPP)弹性体具有优异的阻燃性、抗小分子迁移能力和低发烟量特性,在固体火箭发动机内绝热层中具有潜在应用价值。为预测PDPP复合材料的耐烧蚀性能,首先利用热重曲线计算PDPP复合材料的热解反应动力学参数,然后基于阿伦尼乌斯方程、傅里叶热传导方程和达西定律建立复合材料的烧蚀模型,最后使用COMSOL软件对复合材料的烧蚀过程进行数值仿真,预测复合材料在给定工况下的温度分布、热解程度分布、孔隙压力分布、热解气体质量通量分布和烧蚀表面退移。结果表明,计算所得线烧蚀率为0.067 mm/s,与氧-乙炔试验结果对比误差为11.7%。PDPP复合材料烧蚀过程中的温度分布会影响基体的热分解反应,使热解层的位置逐渐向底面移动,相应地最大孔隙压力和热解气体质量通量区域逐渐向材料内部移动且两者数值逐渐减小。

Poly(diaryloxyphosphazene)elastomer has potential application value in the thermal insulation layer of solid rocket motor with excellent flame retardancy,anti-small molecule migration ability and low smoke emission characteristics.To predict the ablative resistance of poly(diaryloxyphosphazene)composites,the kinetic parameters of pyrolysis reaction of composites were calculated by thermogravimetric curve.Then the ablation model of composites was established based on Arrhenius equation,Fourier heat conduction equation and Darcy law.Finally,the ablation process simulation of the composites was numerically simulated out by COMSOL software.The temperature distribution,pyrolysis degree distribution,pore pressure,pyrolysis gas mass flux distribution and ablation surface recession of the composites were predicted under the given working condition.The results show that the calculated linear ablation rate is 0.067 mm/s,and the error is 11.7%compared with the results of oxyacetylene test.The temperature distribution during the ablation of poly(diaryloxyphosphazene)composites will affect the thermal decomposition reaction of the matrix,making the position of the pyrolysis layer gradually move to the bottom surface.Accordingly,the maximum pore pressure and pyrolysis gas mass flux area gradually move inward,and their values gradually decrease.