Three-dimensional measurement of a gas flow temperature field using far-infrared band CT techniques

Emission spectral tomography (EST) can be utilized to reconstruct three-dimensional (3D) physical parameter distributions of gas flow fields. Mostly, the radiant energy of the visual and near-infrared bands is received by a video camera in EST, so it is difficult to examine a low/medium-temperature gas flow field by normal EST. However, the far-infrared radiant energy of a low/medium-temperature gas flow field is strong enough to be received by a far-infrared detector. Based on EST, a far-infrared band computed tomography (FICT) approach is proposed that focuses on far-infrared spectral emission and band emission tomography. Both low- and medium-temperature blackbody furnaces were adopted to calibrate the relation between infrared thermal image intensity and radiant exitance. The 3D temperature reconstruction of an alcohol blow lamp was carried out. According to the results of multiple measurements, the relative error of the FICT approach is less than 20%. The experimental results prove the feasibility of the FICT approach.