C/C复合材料在超声速富氧烧蚀环境下的烧蚀试验方法研究

Ablation test method for C/C composites in supersonicoxygen-enriched ablation environment

利用氧/煤油液体火箭发动机设计原理,构建了烧蚀热环境可控的内流场超声速富氧烧蚀试验方法,并采用烧蚀发动机点火试验与CFD数值模拟相结合的方法,对所构建的烧蚀试验方法及数学模型的可靠性进行分析与验证,并进一步分析了烧蚀试验过程中的关键烧蚀热环境特性参数。然后,对三维四向编织C/C复合材料在超声速富氧烧蚀环境下的耐烧蚀性能与烧蚀机理进行分析。研究表明,烧蚀热环境的变化会对材料的耐烧蚀性能及烧蚀机制产生一定程度的影响,在收敛段高温、低速的烧蚀热环境下,C/C复合材料的线烧蚀率相对较低,约6.50×10^(-3) mm/s,材料的烧蚀以热氧化烧蚀为主;在烧蚀试样喉部直段区域,C/C复合材料的线烧蚀率逐渐增加,达到了1.35×10^(-2) mm/s,此时,材料的烧蚀体现为热氧化烧蚀后的机械剥蚀;在烧蚀试样扩张段区域,燃气速度急剧增加后,C/C复合材料的线烧蚀率显著增加,在试样出口达到了2.61×10^(-2) mm/s,材料的烧蚀主要体现为机械剥蚀。

A supersonic oxygen-enriched ablation test method for the controllable internal flow-field of the ablation thermal environment was constructed by using the design principles of oxygen/kerosene liquid rocket engines.Then,a combination of ablation engine ignition test and CFD numerical simulation was used to analyze and validate the reliability of the constructed ablation test method and mathematical model,and further analyze the key ablation thermal environment characteristic parameters during the ablation test process.Then,the ablation resistance and ablation mechanism of three-dimensional four-way braided C/C composites under supersonic oxygen-enriched ablation environment were analyzed.The results show that changes in the ablative thermal environment can have a certain degree of impact on the material’s ablation resistance and mechanism.In the convergent high-temperature and low-speed ablative thermal environment,the linear ablation rate of C/C composites is relatively low,about 6.50×10^(-3) mm/s,and the material’s ablation is mainly thermal oxidation ablation.In the straight section area of the ablation specimen throat,the linear ablation rate of C/C composites gradually increases,reaching 1.35×10^(-2) mm/s.At this time,the ablation of the material is manifested as mechanical ablation after thermal oxidation ablation.After a sharp increase in gas velocity in the expansion section of the ablation sample,the linear ablation rate of C/C composites significantly increased,reaching 2.61×10^(-2) mm/s at the sample outlet,and the main manifestation of material ablation is mechanical ablation.