A swirler assembly comprising: a ferrule body comprising 1) a base having an upper surface and a lower surface, and having a centrally-positioned opening formed therein, 2) a ferrule extending from the upper surface and the central opening, and a unitary swirler body comprising: 1) a first swirl section having a plurality of angularly directed primary passages, 2) a second swirl section comprising a venturi and a plurality of oppositely-angled, directed secondary passages disposed coaxially around the venturi, characterized in that: the base of the ferrule body is substantially square in shape and comprises four outer side edges (45,46,47,49) defining a perimeter and corners of the base, the four outer side edges comprising opposed first and second side edges, the ferrule body further comprising: 3) a plurality of protrusions positioned at each corner of the base along the upper surface of each side edge (46, 47), and extending from each corner inwardly for a portion of the length of each side edge (45,46,47,49), the unitary swirler body further comprising: 3) a pair of rails, each comprising an inwardly-extending flange, each formed on opposite sides of the venturi, wherein the rails engage the protrusions along the opposite sides edges (46,47) of the ferrule body to limit separation of ferrule body and the unitary swirler body. a ferrule body comprising 1) a base having an upper surface and a lower surface, and having a centrally-positioned opening formed therein, 2) a ferrule extending from the upper surface and the central opening, and 1) a base having an upper surface and a lower surface, and having a centrally-positioned opening formed therein, 2) a ferrule extending from the upper surface and the central opening, and a unitary swirler body comprising: 1) a first swirl section having a plurality of angularly directed primary passages, 2) a second swirl section comprising a venturi and a plurality of oppositely-angled, directed secondary passages disposed coaxially around the venturi, characterized in that: the base of the ferrule body is substantially square in shape and comprises four outer side edges (45,46,47,49) defining a perimeter and corners of the base, the four outer side edges comprising opposed first and second side edges, the ferrule body further comprising: 3) a plurality of protrusions positioned at each corner of the base along the upper surface of each side edge (46, 47), and extending from each corner inwardly for a portion of the length of each side edge (45,46,47,49), 1) a first swirl section having a plurality of angularly directed primary passages, 2) a second swirl section comprising a venturi and a plurality of oppositely-angled, directed secondary passages disposed coaxially around the venturi, characterized in that: the base of the ferrule body is substantially square in shape and comprises four outer side edges (45,46,47,49) defining a perimeter and corners of the base, the four outer side edges comprising opposed first and second side edges, the ferrule body further comprising: 3) a plurality of protrusions positioned at each corner of the base along the upper surface of each side edge (46, 47), and extending from each corner inwardly for a portion of the length of each side edge (45,46,47,49), the unitary swirler body further comprising: 3) a pair of rails, each comprising an inwardly-extending flange, each formed on opposite sides of the venturi, wherein the rails engage the protrusions along the opposite sides edges (46,47) of the ferrule body to limit separation of ferrule body and the unitary swirler body. 3) a pair of rails, each comprising an inwardly-extending flange, each formed on opposite sides of the venturi, wherein the rails engage the protrusions along the opposite sides edges (46,47) of the ferrule body to limit separation of ferrule body and the unitary swirler body.