Static mixer

In combination with a hollow tubular conduit defining an internal longitudinal passageway wherein said conduit includes an internal wall surface, a static mixing device positioned in said conduit and within a fluid stream having a longitudinal flow direction within said passageway, comprising;

• a circular flange radially inwardly extending into said passageway at a generally normal angular relationship to said conduit internal wall surface, said flange having a central opening defined by an inner peripheral edge of said flange which in turn is inwardly spaced from said conduit internal wall surface for passage of said fluid stream therethrough, said device further including at least two opposed spaced apart flaps radially inwardly projecting from said flange and cooperatively forming said central opening with said flange inner peripheral edge and wherein said flaps are inclined at an angle to said internal wall surface in the direction of said fluid stream, wherein said central opening, said flange inner peripheral edge and said flaps are all defined by circumferential portions of circles of varying diameters and wherein said central opening is defined by a continuously rounded peripheral edge surface, wherein a pair of flaps are provided and said central opening is dumbbell shaped.