双红外激光测温定标源样品温度场对测量结果的影响

Influence of Sample Temperature Field of Double Infrared Laser Temperature Calibration Source on Measurement Results

双波长红外激光测温技术可实现免发射率的温度测量,仪器常数是此技术的核心参数。目前,仪器常数的确定依赖于定标样品表面的中心点温度,当对定标样品表面的探测位置偏离其中心点时,仪器常数的结果会产生影响。对定标样品进行数值建模,分析不同样品温度场的分布及其对测量结果的影响规律。结果表明:样品的前表面呈现近似中心对称的温度分布,中心温度低,边缘温度高,温度由中心向边缘上升的趋势随着半径方向先迅速上升,后缓慢上升;在温度1173 K下进行定标,定标位置偏移±5 mm时,高温合金、低发射率涂层样品和SiC所标定的仪器常数产生的影响分别为1.87%、1.06%和0.79%;在873~1073 K测温范围内,高温合金、低发射率涂层样品和SiC由于仪器常数偏移导致的测温平均相对偏差分别为:0.34%、0.20%和0.14%。

Active dual-wavelength infrared laser temperature measurement can realize emissivity free temperature measurement.The instrumental constant is the core parameter of the temperature measuring system.At present,the determination of the instrumental constant depends on the temperature of the center point on the surface of the calibration sample.In the process of temperature measurement and calibration,when the detection position of the surface of the calibration sample deviates from its central point,the result of the instrument constant will be affected.But the temperature field distribution outside the central point and its influence on the temperature measurement results are scarce.Therefore,The numerical modeling of the calibration samples is carried out to analyze the distribution of temperature fields of different samples and their influence on the measurement results.The results show that the temperature distribution on the front surface of the sample is approximately center-symmetric.The center temperature is low and the edge temperature is high.The temperature from the center to the edge increases rapidly first and then slowly with the direction of the radius.The influence of different deviation degree of calibration sample position on the instrumental constant is analyzed.When the calibration temperature is 1173 K and the calibration position offset is±5 mm,the effects of the calibrated instrumental constants of superalloy,low emissivity coating sample and SiC are 1.87%,1.06%and 0.79%,respectively.The influence of the instrumental constant on the temperature measurement results is further analyzed.The mean relative deviations of the superalloy,low emissivity coating sample and SiC due to the instrumental constant deviation are 0.34%,0.20%and 0.14%,respectively,in the temperature measurement range of 873~1073 K.