热阻塞效应在有机硅树脂-碳纤织物复合材料烧蚀防热中的作用

为评价热阻塞效应对有机硅树脂-碳纤织物复合材料防热的贡献，根据有机硅树脂的烧蚀防热机理建立热响应过程数学模型，预测了有机硅树脂-碳纤织物复合材料的背面温度以及有机硅树脂的热物性参数，重点分析了热阻塞效应对有机硅树脂-碳纤织物复合材料防热性能的影响。结果表明在400 kW/m2的热流烧蚀下，有机硅树脂-碳纤织物复合材料40 s前热阻塞效应大部分来自有机硅树脂分解产生的引射气体，40 s后则完全来自于炭燃烧产生的引射气体；阻塞因子在10 s时达到最小，此刻阻挡了121.6 kW/m2的热流进入有机硅树脂内，在整个烧蚀过程中热阻塞效应减少了4.1%的总热量进入有机硅树脂内；在热物性参数中，热阻塞效应对有机硅树脂密度影响最大，导热系数和比热容次之；与增加逸出气体质量流率相比，延长有机硅树脂逸出气体的时间更能显著提高热阻塞效应，达到更好的防热效果。 

Effect of heat blockage on ablative thermal protection of silicone resin-carbon fiber fabrics

To evaluate the contribution of the thermal blocking effect to the heat protection of silicone resin-carbon fiber fabrics composites, a mathematical model of the thermal response process was established based on the ablation and thermal degradation behavior of silicone resin. The temperature of the back side of the silicone resin-carbon fiber fabrics composite and thermo-physical parameters of the silicone resin have been predicted by this model. The analysis of the thermal blocking effect on the thermal performance of silicone resin-carbon fiber fabrics composite was mainly focused on. The results show that when the silicone resin-coated carbon fiber fabrics are ablated under 400 kW/m2 heat flow, most of the thermal blocking effect comes from the ejection gas generated by the decomposition of the silicone resin in 40 s, and it completely comes from the ejection generated by carbon combustion after 40 s. The blocking factor reaches the minimum at 10 s, which blocks 121.6 kW/m2 heat flow into silicone resin. During the entire ablation process, the thermal blocking effect reduces 4.1% percent of the total heat entering the silicone resin. Among the thermophysical parameters, the thermal blocking effect has the greater influence on the density of the silicone resin than its thermal conductivity and specific heat capacity. Compared with increasing the mass flow rate of the pyrolysis gas of the silicone resin, prolonging the time for the silicone resin to escape the gas can significantly improve the thermal blocking effect and achieve a better heat protection effect.