基于裸装热电偶的开放油池火焰测温误差修正方法

Error Correction Method of Pool Fire Temperature Measurement in Open Space Based on Bare-bead Thermocouple

为了准确地测量开放环境中油池火烧实验的火焰温度,本文建立了开放池火中裸装热电偶的火焰测温修正模型,并对测温误差的主控机制进行识别。以煤油燃料为例,分析了不同火焰包覆厚度的火焰辐射特性,探究了典型火焰温度下火焰包覆厚度、热电偶辐射率和环境温度对测温误差的影响规律。结果表明:火焰辐射率随着火焰包覆厚度的减小而呈现指数级减小的变化趋势;作为模型的主控参数,火焰包覆厚度的减小导致测温误差急剧增加,最大可达258.6 K。在此基础上提出了煤油火烧实验中需要对测温误差进行修正的热电偶火焰包覆厚度界限值;较高的热电偶辐射率会导致更大的测温误差,而开放环境温度的波动对测温误差的影响几乎可以忽略。

In order to accurately measure the flame temperature of pool fire experiment in open space,a modified flame temperature measurement model of bare-bead thermocouple in open pool fire is established in this paper,and the main control mechanism of temperature measurement error is identified.Taking kerosene fuel as an example,the flame radiation characteristics of different flame thicknesses were analyzed,and the influence rules of flame thicknesses,thermocouple emissivity and surrounding temperature on temperature measurement errors were explored.The results show that the flame emissivity decreases exponentially with the decrease of flame thickness.As the main control parameter of the model,the decrease of flame thickness leads to a sharp increase in temperature measurement error,the maximum is 258.6 K.On this basis,the limit value of flame thickness of thermocouple which needs to correct the temperature measurement error in kerosene burning experiment is put forward.Higher thermocouple emissivity will lead to larger temperature measurement error,and the influence of open space temperature fluctuation on temperature measurement error is almost negligible.