热电偶延误量特性研究

Analysis of thermocouple delay characteristics

用热电偶进行温度动态测试时常用阶跃温度信号作为激励信号,而阶跃温度施加在热电偶表面的时刻与热电偶开始响应输出的起始时刻存在一定的延迟量,且该量值对热电偶的动态特性具有较大的影响。为了探究该延迟量与热电偶动态特性的关系,研究以激光器作为激励源,得到了温度上升时间小于20μs的阶跃温度信号。用微透镜阵列对激光光束进行均匀化处理,使光斑内能量均匀分布。用高速辐射温度计实时监测偶结表面的温度,得到了精确温度下的热电偶动态特性。最后对3种不同直径的K型热电偶和C型快速响应热电偶进行了对比实验,分析了不同条件下延误量与热电偶时间常数的关系,为热电偶接触式测温精度和动态特性的提升提供了参考。

The step temperature signal is often used as the excitation signal when thermocouple is used for temperature dynamic testing.There is a certain delay between the moment when the step temperature is applied on the thermocouple surface and the initial moment when the thermocouple begins to respond to the output.And the value has a great influence on the dynamic characteristics of the thermocouple.In order to explore the relationship between the delay and the thermocouple dynamic characteristics,uses the laser as the excitation source to obtain the step temperature signal with temperature rise time less than 20μs.The laser beam is treated uniformly by the homogenization module to make the power evenly distributed in the spot.A highspeed radiation thermometer was used to monitor the thermocouple surface temperature in real time and the thermocouple dynamic characteristics at precise temperature were obtained.Comparison experiments were carried out on three kinds of K-type thermocouples with different wire diameters and C-type quick-response thermocouples,and the relationship between the delay and the thermocouple time constant under different conditions was analyzed,which provided a reference for improving the temperature measurement accuracy of thermocouple contact type.