不同热控涂层的飞艇散热器Fluent仿真分析

为了分析不同热控涂层的性能，采用Fluent模拟了临近空间飞艇上小型散热器在20 km高空的热平衡状态。散热器分别使用S781白漆、S956灰漆及La_1-xSr_xMnO₃化合物热致变材料作为热控涂层，使用UDF（User defined function）编码对热控涂层设置随涂层温度变化的发射率。经过模拟计算，得到了在太阳垂直照射与无太阳辐射两种极端情况下不同热控涂层散热器的温度分布。仿真结果得出在太阳垂直照射下，使用La_1-xSr_xMnO₃化合物作为热控材料散热器的锂电池温度处于最佳工作温度范围，但其在太阳垂直照射与无太阳辐射情况下电源的平均温度温差为8.89 K，略大于S781白漆的温差6.57 K。模拟中，La_1-xSr_xMnO₃热致变材料发射率变化较小，约为0.11，垂直照射时温度最高的散热区域发射率可达到0.8，无太阳辐射时温度最低的散热区域约为0.69。

Fluent Simulation Analysis of Airship Radiator with Different Thermal Control Coatings

In order to contrast the properties of diverse thermal control coatings, Fluent is used to simulate the thermal balance of small radiators in the near space at a height of 20 km. Respectively, S781 white coating, S956 gray coating and La_1-xSr_xMnO₃ compound thermotropic materials are used as the thermal control coatings of the radiator. The UDF (User defined function) code is employed in setting the emissivity of the thermal control coating which varies with the change of temperature. Through the simulation, the temperature distribution of radiators in two extreme conditions, vertical solar radiation and no solar radiation, is obtained. The simulation results show that the temperature of the lithium battery of the radiator using the La_1-xSr_xMnO₃ compound as a heat-control material is within the optimum working temperature range under the vertical solar radiation. But its difference of the power''s average temperature in two situations is 8.89 K, larger than that of S781 white coating 6.57 K. During the simulation, the emissivity of La_1-xSr_xMnO₃ thermochromic material has a small change of about 0.11, and the emissivity of the highest temperature in heat dissipating region can reach 0.8 in vertical irradiation condition, while 0.69 at the lowest temperature in no solar radiation circumstance.