Quantitative Evaluation of Flow Computations by Rainbow Schlieren Deflectometry

Abstract

Rainbow schlieren deflectometry, a line-of-sight optical measurement technique, was used to evaluate computations of steady nonreaeting and reacting flows in axisymmetric systems. The nonreacting flow was that of an isothermal helium jet discharged vertically in air, and the reacting flow was that of a hydrogen jet diffusion flame. The computed results were processed to obtain a color schlieren image for direct visual comparison with the corresponding experimental color schlieren image. The computed and measured angular deflections of light rays were also compared. In addition, the computed field distributions of scalar flow properties including the refractive index, species concentration, and temperature were compared quantitatively by inverting the experimental schlieren measurements. The results demonstrate the effectiveness of the rainbow schlieren technique in evaluating the physical models used for flow computations