双探针型海底热流计数据解算模型选取

Selecting a simplified model for dual-probe seafloor heat-flow meter

选取适合于双探针型海底热流计数据解算的简化模型,是双探针型海底热流计结构优化的理论基础,对提高海底热流数据解算精度具有重要意义。本文基于脉冲式双探针海底工作的有限元数值模型,对双探针的脉冲加热时间、体生热率、热物性、长度及半径等因素在双探针脉冲法的3个线热源简化模型中所引起的模型误差作了详细的分析和讨论,并以模型误差最小为原则选取简化模型。结果表明:1)脉冲加热有限长线热源(PFLS:pulsed finite line source)模型是双探针脉冲法中较为实用的简化模型,它可消除加热时间和探针长度对介质热物性参数求解的影响;2)在PFLS模型下,探针热导率对待测介质热物性测量的影响可以忽略;而探针间距越大、半径越小及其体积比热容与待测介质越接近,则所求介质热物性的模型误差就越小;在保证温度传感器能有效记录到温度变化的前提下,探针脉冲功率的大小基本不影响介质热物性求解的模型误差。

Selecting an effective and convenient simplified model for dual-probe seafloor heat-flow meter is the theoretical basis for optimizing dual-probe structure, which is very important to improve heat-flow calculation ac- curacy. Basing on the finite element numerical model about seafloor pulsing dual-probe, the authors analyzed in detail how the dual-probe＇s heat pulse duration, heat generation rate, thermal properties, length and radius affect model errors in three line source simplified models. The selected effective and convenient simplified model is the one whose model errors are the least. The results are as follows： 1 ） in dual-probe heat pulse method, Pulsed Finite Line Source （PFLS） model is a more practical simplified model, in which the model errors from pulse du- ration and probe length can be avoided; 2） in the PFLS model, model errors from probe thermal conductivity can be neglected. In addition, model errors can recede with probe spacing increasing, probe radius decreasing and probe volume heat capacity approaching the surrounding medium. When surrounding medium temperature change can be detected and recoded effectively by the sensor probe, probe heat pulse power cannot affect model errors.