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为研究用于钝头体高超声速飞行器热防护系统的碳/酚醛复合材料在典型服役环境下的烧蚀机制,首先,建立了烧蚀行为的数学模型,模型考虑了材料表面热辐射、固体相的温升吸热、基体热解反应吸热、高温热解气体引射、质量引射引起“热阻塞”效应、热解气体的温升和膨胀吸热等多种能量耗散机制,并利用有限元方法实现了数学模型的求解;然后,预报了在冷壁热流为400kW·m~(-2)、焓值为5MJ·kg~(-1)的气动热环境下碳/酚醛复合材料的烧蚀行为。结果表明:在受热过程中,厚度为20mm的碳/酚醛复合材料碳化层的深度持续增加,100s时的表面温度达到1 420K,背壁温度为346K,热解气体压力达10.3atm,碳化层深度为7.50mm。所得结论可为具有长时间大面积热防护需求的高超声速飞行器的热防护系统设计提供支持。
In order to study the ablation mechanism of carbon / phenolic composite used in the thermal protection system of blunt body hypersonic vehicle under typical service environment, a mathematical model of ablation behavior was established. The model considered the surface thermal radiation, solid phase Thermal absorption of temperature rise, endothermic reaction of matrix pyrolysis, high temperature pyrolysis gas injection, mass ejection caused “thermal blockage ” effect, pyrolysis gas temperature rise and expansive heat absorption and other energy dissipation mechanisms, and The finite element method was used to solve the mathematical model. Then, the carbon / phenolic composite material was predicted under the aerodynamic heat environment with a heat flux of 400kW · m -2 on the cold wall and an enthalpy of 5MJ · kg -1 Ablation behavior. The results show that the carbonization depth of carbon / phenolic composites with a thickness of 20mm continuously increases during heating, the surface temperature reaches to 1220K at 100s, the back wall temperature is 346K, the pyrolysis gas pressure reaches 10.3atm, 7.50mm. The results provide support for the design of thermal protection systems for hypersonic vehicles that have large thermal protection needs over a long period of time.