Optical computed tomography is an important technique in the visualization and diagnosis of various flow fields. A
small-scale diffusion flame was visualized using deflection tomography. A projection sampling system was proposed for
deflection tomography to obtain deflectograms with a pair of gratings. Wave-front retrieval was employed for processing
the deflectograms to obtain the deflection angles of the rays. This two-dimensional data extraction method expanded the
application of deflection tomography and was suitable for the projection extraction of small-scale combustion. Deflection
angle revision reconstruction algorithm was used to reconstruct the temperature distributions in 10 cross sections for
each deflectogram in different instants. The flow structure was reconstructed using a visualization toolkit equipped with
the marching cube and ray casting algorithms. The performed experiments demonstrated the three-dimensional dynamic
visualization of temperature distributions and the flame structures of small-scale diffusion combustion.
A new iterative reconstruction algorithm is developed and applied to moiré deflection tomography for flow field measurements. The algorithm is derived from the basic deflection formula and based on a modified algebraic reconstruction technique. The precision and convergence of the algorithm are analyzed through a numerical simulation. To capture multidirectional projection data, a rotatable deflectometric system is developed. The efficacy of the new algorithm is assessed by reconstructing an asymmetric temperature field. Furthermore, the algorithm is employed to investigate the image of a cross section of a free jet containing steep gradients and to reconstruct the density field of the rocket exhausted jet.
Moire tomography is applied in fully quantitative measurement of temperature distribution. Rotary moire deflectometer is designed to capture multidirectional optical projections, and moire patterns of temperature field can be obtained in 180 degrees. Then the temperature distribution of axisymmetric or asymmetric flow field is calculated by a new iterative reconstruction algorithm. The algorithm is derived from an existing moire deflection formula and based on an improved algebraic reconstruction technique. The method is demonstrated by reconstructing a temperature field generated above the top of two electric solding irons.