Influence of particle diameter on numerical PIV measurement using DNS data of turbulent premixed flame

Currently, practical combustors have some problems such as low efficiency and high emissions with harmful effects. To resolve these issues, it is necessary to understand the detailed local flame structure. This study focuses on PIV capable of measuring local flow velocity describing the flame structure. Also, the detailed flame structure could be analyzed by DNS. However, the analysis method of the local flame structure differs between numerical simulations and experimental measurements. Therefore, the quantitative evaluation of the relationship between experimental and numerical analyses still remains in doubt. In this study, PIV analysis was performed in a computational domain with the DNS data of turbulent premixed flames and the local flow velocities from both numerical PIV and DNS were obtained. In the higher density ratio of unburned mixture to burned product, changing the particle diameter under the same condition of the total of brightness in a measurement region, the correlation coefficient became high when the particle diameter was large. This is because the difference in brightness between pixels increases with the particle diameter. In addition, the correlation coefficient increased as the density ratio decreased. This is because the number of particles in the burned side decreases as the density ratio increases.