水素-酸素-アルゴン理論混合気の乱流燃焼速度に与える局所燃焼速度特性の影響

概要

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This study was made to establish a prediction method of turbulent burning velocity for stoichiometric hydrogen-oxygen-argon mixtures, with paying special attention to the importance of local burning velocity to turbulent burning velocity. In this study, stoichiometric mixtures with different dilutions, whose laminar burning velocity SL0 was varied from 25 to 90 cm/s, were used under almost the same weak turbulence condition, so that the ratio of turbulence intensity u' to SL0 becomes 0.4 to 2.0. Nitrogen was also used as a conventional dilution gas for comparison with argon. A two-dimensional sequential laser tomography technique was applied to obtain the relationship between the flame shape and the flame displacement in a constant-volume vessel. The local flame displacement velocity SF of turbulent flames was quantitatively measured as the key parameter of local burning velocity. It was found that the trends of the mean values of SF, SF,m, against u'/SL0 corresponded well to its turbulent burning velocities, but SF,m did not increase infinitely with increasing u'/SL0. The turbulent burning velocity also attempted to be predicted by some empirical equations. As a result, the predicted turbulent burning velocities, where the obtained SF,m was employed instead of SL0 as the local burning velocity, were in good agreement with experimental ones.