Measurement and calculation technology of temperature compensation of explosion flame based on infrared radiation

In testing explosion flame temperature with radiation thermometry, there is relatively great deviation of empirical value of flame emissivity from flame combustion mechanism. Meanwhile, the distance of measure point from the flame and ambient temperature and humidity also cause attenuation of thermal radiation to different extent, affecting the accuracy of measurement of explosion flame’s temperature. With focuses on foregoing two problems and based on atmospheric radiation theory and the law of optics propagation, a model of radiation path attenuation compensation was deduced in accordance with the functional relation among explosion flame’s radiance, digital output value of thermal imager and explosion flame’s temperature, followed by obtainment of relevant parameters i.e. system responsivity in the model from radiometric calibration of thermal imager; then, the applicability of the gray body hypothesis of TNT explosion flame was confirmed by analyzing the composition of the products of TNT explosion flame. Therefore, a function model of explosion flame’s dynamic average emissivity was deduced concerning onsite atmospheric transmittance, digital output value of thermal imager and explosion flame’s temperature measured by the colorimetric thermometer in accordance with the expression of explosion flame’s radiance; finally, based on the receiver function of thermal imager’s effective radiation, a joint temperature compensation evaluation method, which combines radiation path compensation and dynamic emissivity, was proposed for joint inversion of explosion flame’s temperature at the explosion site and the range of temperature error of inversion was obtained through comparison of measured result with explosion flame’s surface temperature measured by colorimetric thermometer. The test result suggests the error of explosion flame’s temperature measured with the proposed compensation model is reduced to 11.292%−59.077% from previous 55.699%−89.847% before compensation, thus effectively improving the accuracy of measurement of transient flame temperature of explosion at external field and providing a means for accurate infrared thermography-based evaluation of thermal effect in explosion field.