飞行试验用双结点热电偶传感器研究及测量误差分析

A dual-junction thermocouple for flight test and its measurement error analysis

高超声速飞行试验气动热测量对快响应、小型化的热流传感器提出了需求,双结点热电偶传感器具有响应快、尺寸小、测量信息丰富等优点,是飞行试验热流测量的优质解决方案。以双结点热电偶传感器为研究对象,开展了传感器测量原理、传感器结构以及测量方法研究,并将该传感器应用于飞行试验模型壁面温度测量。试验结果表明:双结点热电偶传感器可同时测量模型表面温度和背面温度;背温测量误差相对较大,背温测量结点尺寸较大、背温测量结点与模型壁面之间的绝缘涂层是影响背温测量结点热响应的主要原因。针对双结点热电偶传感器,目前尚缺乏相应的热流辨识方法。

The flight test needs fast response and small transducer for heat flux measurement.The dual-junction thermocouple,which is characterized by fast response,small size and abundant measured information,is one of the best solutions for the temperature and heat flux measurement in the flight test.The principle,structure and measurement method of the dual-junction thermocouple are studied,and dual-junction thermocouples are used in a flight test for the model surface temperature measurement.The model front-surface and back-surface temperatures were measured simultaneously by the dual-junction thermocouples,and it is found that the measured back-surface temperature has a greater error.The response time of the back-surface measurement point is much longer than that of the front-surface measurement point,which is affected by the junction size and the insulating coating between the junction point and the model surface.At present there is still a lack of the corresponding heat flux estimation method for the dual-junction thermocouple.