二氧化碳介质气动加热环境下碳化热解类防热材料烧蚀机理分析

目的研究轻质热解类防热材料在高焓CO_2气动加热环境下的炭化层烧蚀机理。方法建立考虑化学反应动力学过程影响的材料热化学烧蚀特性计算方法,研究碳化热解类防热材料在二氧化碳介质气动加热环境下的炭化层烧蚀机理,分析与空气介质环境下的材料烧蚀特性差异,计算得出二氧化碳气体离解、热解引射气体质量流率和组分等因素变化对防热材料烧蚀特性的影响规律。结果 3000K温度下,当压力为1.0×10~5 Pa时,二氧化碳组分和地球大气的无因次烧蚀因子分别为0.26和0.17。结论压力或温度升高、二氧化碳离解程度升高、来流扩散质量流率或热解气体流率减小,均会使材料无因次质量烧蚀率更大,同时烧蚀热效应也发生相应改变。

Impact of Carbon Dioxide Aeroheating on the Ablation Performance of Charring Thermal Protective Materials

The paper aims to study the carbonized layer ablation mechanism of lightweight class pyrolytic heat material in aerodynamic heating environment of high enthalpy CO2. The ablation performance predicting method considering the kinetics of reaction was established and used to analyze the charring layer ablation mechanism under high temperature carbon dioxide. The difference of the materials ablation performance between the carbon dioxide and air aeroheating was analyzed. The impact of carbon dioxide dissociation, and the mass flow and composition of the pyrolysis gases on the materials ablation was obtained through computing. When the gas pressure and the wall temperature reached 1.0×105 Pa and 3000 K, the non-dimensional ablation rates under the CO2 and air were 0.26 and 0.17, respectively. The non-dimensional ablation rate of the materials become higher with the increase of temperature, pressure, or dissociation degree of CO2, and the reduction of the mass flow rate of the flow or pyrolysis gases or the non-dimensional ablation rate of the materials. The heat of ablation changes at the meantime.