Predication and wind tunnel experimental verification of thermal protection performance for low density ablative material in medium thermal environment
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摘要: 低密度烧蚀材料是为解决飞船再入过程中高焓、低热流长时间飞行热环境的防热问题开发的防热材料。随着新工程项目的开展,低密度烧蚀材料被要求应用于中高热流的新环境下。在电弧风洞上开展了低密度烧蚀材料在气流恢复焓为18MJ/kg,冷壁热流为720kW/m2的高焓、中高热流条件下的防热性能考核试验。试验中改进了传统的水冷框方式,水冷框与试验件之间增加了高性能隔热材料,避免了侧向热泄漏,提高了试验结果的准确性。试验结果表明低密度烧蚀材料能够满足中高热流的加热环境。同时开展了低密度烧蚀材料的防热性能计算研究。低密度烧蚀材料的烧蚀机理复杂,根据低密度烧蚀过程的本体热传导-热解-炭化机制,不同区域和阶段分别采用对应的预测方法,改进了炭化烧蚀的计算方法。将理论预测结果同风洞试验结果进行了对比研究,结果表明理论预测同风洞试验结果一致性良好。Abstract: Low density ablative material is developed to shield the spaceship from the high-enthalpy, low heating rate thermal environment during re-entry. As new vehicle projects develop, the low density ablative material is required to be able to work in the new medium thermal flux environment. In this paper, material test pieces are evaluated in the arc heated wind tunnel with high-enthalpy, medium thermal condition. In the experiment, high-performance insulation material is installed between the water-cooled frame and test pieces, which avoids lateral thermal leaking and improves the accuracy of the experiment. It shows the competence of the low density ablative material under the new thermal condition in experiments. At the same time, the calculation is carried out to evaluate the thermal protection performance of this material. The ablative mechanism of the low density ablative material is very complicated. In this paper, the computation method for carbonization ablation is improved by making use of different predication methods in different regions, based on the heat conduction-pyrogenation-carbonization mechanism of the low density ablative material. The theoretical prediction is compared with the data from wind tunnel experiments, showing that the prediction is consistent with the wind tunnel result.
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表 1 炭化层厚度比较
Table 1 Comparison of carburization zone thickness
试件状态/mm 来源 炭化层厚度/mm 16 试验 4.10 计算 5.11 12 试验 6.70 计算 5.08 -
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