DNS analysis on local burning velocity and flame displacement speed of turbulent premixed flames with different density ratio

To investigate the relationship between local burning velocity and flame displacement speed with different density ratio, a numerical analysis was performed using DNS databases of statistically steady and fully developed turbulent premixed flames. The local burning velocity based on fuel consumption rate is considered to be most appropriate as the definition of burning rate because combustion is a kind of chemical reactions. Since it is impossible, however, that the local burning velocity is obtained experimentally by using any present measurement technology, the numerical results using the local burning velocity cannot be compared with any experimental data. Hence the flame displacement speed, which can be obtained and compared easily with experiments, has previously been used for numerical analyses. Thus, to realize comparison of numerical results using the local burning velocity with some experimental ones, it is necessary to reveal the relationship between the local burning velocity and the flame displacement speed.