同位素热源火灾事故环境模拟试验及仿真分析

为考核空间同位素热源火灾事故安全性，开展了同位素热源火灾模拟试验及数值仿真研究。提出了同位素热源火灾模拟试验及试验系统设计的相关方法；对热源火烧环境热响应特性进行了数值仿真，探讨了预热阶段产品表面辐射率、对流换热系数等的影响，以及运输及发射剖面火灾事故热源热响应特征；基于仿真结果开展了某空间同位素热源火灾模拟试验。结果表明，预热阶段，产品温度主要受目标预热温度、表面辐射率等因素影响；火烧阶段，产品烧蚀层温度上升较快，发射场事故下热源各层温升速率较运输事故下的大，但放射性同位素芯块仍处于安全温度；试验中火焰呈火羽流形态，具有大尺度 低频率扰动特征，火焰熄灭30 min后，热源表面温度降至约180 ℃，整体结构良好。

Environmental Simulation Test and Numerical Simulation on Radioisotope Heat Unite in Fire Accident

In order to ensure the safety of space radioisotope heat unite in fire accidents, environmental simulation tests and numerical simulation analysis on the radioisotope heat unite in fire accidents were performed. The method of environment test and apparatus design was proposed, and numerical analysis on heat transfer characteristics of the product during the test was carried out. Based on the numerical results, the fire test on a type of radioisotope heat unite was carried out. The results show that the preheating temperature significantly affects thermal response characteristics of isotope heat source, and the emissivity of the product surface mainly affects the temperature of the ablation layer. In addition, the temperature of the ablation layer of the product rises rapidly in fire accidents, and the temperature rise rates of each layer in the launch site accident are higher than those in the transport accident, but the pellets are still at a safe temperature in fire accidents. The test shows that the flame has the shape of plume and has the characteristics of large scale-low frequency disturbance character. Finally, the surface temperature of product drops to 180 ℃ and the product has a complete structure 30 min after the flame extinguished.