3D Printing of Instantaneous Turbulent Flame Shapes, Experimentally Captured by 3D Computer Tomography and Multi Directional Schlieren Photography

Abstract

Nonscanning 3DCT(Computer Tomography) technique employing a multidirectional quantitative schlieren photographic system(topleft picture) with flash light source, has been performed to obtain instantaneous density distributions of highspeed turbulent flames(for reference, the target flame of 8 m/s exit velocity is indicated in the righttop picture). For simultaneous schlieren photography, the custommade 20directional schlieren camera was constructed and used. The target turbulent flame is highspeed flames, anchored on the burner of a nozzle exit of 4.2 mm diameter. The image set of 20 directional schlieren images are processed by MLEM CTalgorithm to obtain the 3D reconstruction of instantaneous density distribution. The solid models(bottom picture) of threshold density level of 0.7 kg/m3 are 3Dprinted as 4 times large size for detail observations. The average exit velocity of the propaneair mixture of equivalence ratio of 1.1 is set to be 10, 8, 6 and 4 m/s (models from left to right in the bottom picture). The solid models show the complicated shape of the high speed turbulent flames. The flame structure of higher speed flame has fine scale corrugations. This corresponds to the “corrugated flamelets regimeâ€‌ of the Borghi & Peters diagram well.