太阳辐照度绝对辐射计吸收腔结构优化

摘要

为了获得太阳辐照度绝对辐射计中吸收腔的最优结构参数,需要对结构中吸收腔-热连接-热沉构成的传热链进行热分析.基于Ansys软件的有限元方法,给出了上述传热链的仿真模型,并计算得到了仿真结构的温度响应曲线;通过改变吸收腔的结构参数(尺寸、材料等),探究了不同参数下传热状态的变化及其原因;通过分析仿真结果确定了吸收腔最优结构参数.仿真结果表明:在环境温度为常温(298 K)、加热功率为50 mW的情况下,吸收腔最优结构参数为壁厚0.07 mm/锥顶角30°/帽檐宽度2.2 mm/银质,此时辐射计的时间常数为11.501 s、响应度为1.391 K;同等条件下进行实验,测得时间常数为11.487 s,响应度为1.397 K,与仿真结果相比,误差分别为0.12％和0.43％.仿真结果基本符合理论推导,所得数据具有足够的可靠性,证明该模型可以指导绝对辐射计优化设计,提高其工作性能.%In order to obtain the optimal structural parameters of the absorption cavity of Solar Irradiance Absolute Radiometer(SIAR),a study was carried out on the thermal circuit of the SIAR,which was constituted of the cavity,thermal link and heat sink.Based on the finite element method by using Ansys software,a reliable model of this thermal circuit was introduced.The temperature response curves of the model were consequently obtained.Then the effects of structural parameters of the cavity,e.g.sizes and materials were investigated on the SIAR's thermal performances,and optimal structural parameters of the cavity were proposed.Simulation results indicate that at the ambient temperature of 298 K and heating power of 50 mW,the optimal parameters of cavity are silver with a wall thickness of 0.07 mm,a cone angle of 30° and a brim width of 2.2 mm,and when the thermal time constant is 11.501 s,the responsibility is 1.391 K.Experiments are carried out under the same conditions:the time constant and responsibility of measurement are 11.487 s and 1.397 K.Compared with simulation results,the differences are 0.12％ and 0.43％,respectively.The simulation results are in accordance well with the theoretical derivation,and the results are sufficiently reliable,so that this model can be used to conduct the optimation design of the absolute radiometer and improve its performance.