高速飞行器轻质防热材料高温环境下的隔热性能研究

Research on insulation properties of high-speed aircraft lightweight heat-resistant materials in high-temperature environment

导弹等高速飞行器广泛采用轻质材料进行热防护,但实际使用的轻质防热材料由于在密度、质量、工艺、生产批次等多方面的原因,厂家提供的非连续表征的离散式材料导热系数,与非线性连续变化的实际热参数之间存在一定差别。建立轻质防热材料高温导热系数测量装置,通过试验得到轻质高温陶瓷隔热材料导热系数与温度之间的非线性关系,为提高数值计算的准确性提供依据。文中还通过建立有限元模型,并使用由试验得到的温度与导热系数之间的非线性关系对轻型高温陶瓷隔热材料的隔热效果进行数值模拟;同时使用瞬态气动热试验模拟系统对上述防热材料进行气动热模拟试验,将计算结果和试验结果进行对比验证。研究表明,数值计算和试验结果取得了良好的一致性,说明采用实测的导热系数与温度之间的非线性关系进行数值模拟可得到更为准确的计算结果,该工作使理论计算能够在一定程度上替代价格昂贵的气动热模拟试验打下可靠基础。

Lightweight materials are widely used in missiles and other high-speed aircrafts for thermal protection.As the actual lightweight heat-resistant materials differ in density,quality,technology,production batches and other aspects,the piecewise discrete thermal conductivities provided by the manufacturer are normally quite different from actual values of the materials.In this paper,in order to provide reliable thermal conductivities suitable for accurate numerical simulation,a high-temperature thermal conductivity measuring device was established for lightweight heat-resistant materials.Moreover,using nonlinear relationship between the temperature and thermal conductivity obtained by experimental method,the heat insulation effect of lightweight high temperature heat-resistant ceramic materials was numerically simulated by FEM.And the heat-resistant materials mentioned above were also tested by the transient aerodynamic heating simulation experimental system,and comparison between the results of calculation and experiment was carried out.There is satisfactory agreement between calculation and experiment.It indicates that more accurate caculated results can be obtained by using the nonlinear relationship between temperature and the thermal conductivity measured.The study above lays a solid basis for replacing costly transient aerodynamic heating simulation testing using numerical simulation.