Evaluation of fractal dimension for mixing and combustion by the schlieren method

The evaluation of fractal dimension values from schlieren flow images has been investigated. It was found for passive mixing heated jet flows that a value of 2.31, close to that obtained by tomographic imaging, was obtained. For turbulent diffusion flames a value of 2.40 was obtained, and this increased slightly with axial movement and with acoustic excitation of the flame. Broadly counteracting effects due to the transverse differentiation and integration along the imaging beam inherent in the schlieren method was found to arise.