Development of Combined Optical System for Thermal Analysis of Impinging Flames

Three-dimensional density distributions of an impinging and eccentric flame have been analyzed numerically and experimentally by a combined optical system with a digital speckle tomography. The flame has been ignited by premixed butane/air from air holes and impinged vertically against a plate located at the upper side of the burner nozzle. In order to compare with experimental data, computer synthesized phantoms of impinging and eccentric flames have been derived and reconstructed by a developed three-dimensional multiplicative algebraic reconstruction technique (MART). A new scanning technique has been developed for the analysis of speckle displacements to investigate wall jet regions of the impinging flame including sharp variation of the flow direction and pressure gradient. The reconstructed temperatures by the digital speckle tomography have been compared with a temperature photography by an infrared camera and results of a numerical analysis using a finite element method.