Swirl generator effect on a confined coaxial jet characteristics

Results show that for an annular swirl generator, the swirler location in the central pipe affects considerably the dynamic structure and the mixing process in the confined volume. Moreover, it has been shown that the optimal swirler position depends on the intended application: For non reacting case, the central pipe outlet is judged as the best test case to guarantee good mixing process. On the contrary, for reacting case, the annular swirler should be placed far from the main pipe outlet to ensure better mixture and avoid flashback problem caused by flattened radial concentration profiles. By modifying the central jet type (Helium, hydrogen and methane), it has been proven that hydrogen tends to mix more rapidly. However, the flattened radial concentration profiles problem persists for the different gases. Meanwhile, this problem can be solved by modifying the geometry of the swirler placed at the central pipe outlet.