A method of controlling a fluid flow using momentum and/or vorticity injections. Actively controlling an actuator allows for direct, precise, and independent control of the momentum and swirl entering into the fluid system. The perturbations are added to the flow field in a systematic mater providing tunable control input, thereby modifying behavior thereof in a predictable manner to improve the flow characteristics.

A vortex ring generation device includes a casing and an extrusion mechanism. The casing has a gas passage and a discharge port. The extrusion mechanism extrudes gas in the gas passage such that the gas in a vortex ring shape is discharged from the discharge port. V (m.sup.3) represents an extrusion volume, D (m) represents a diameter of the discharge port, L (m) represents a length of a cylinder having the diameter D and the volume V, and U (m/s) represents a discharge flow rate 0.045≤D≤0.135, 0.15≤L≤0.35, and 3≤U≤5.

A system and a method for reducing drag on the aft-fuselage of an aircraft are provided, which system and method utilize at least one finlet provided on each side of the aft-fuselage of an aircraft for reducing drag—on the aft-fuselage, which finlets are (i) positioned at the rear half of an upswept portion of the aft-fuselage starting at a breakline, (ii) positioned in the path of the vortices generated by the aft-fuselage, and (iii) oriented at 1 to 9 degrees angle relative to the local airflow about the aft-fuselage of the aircraft to straighten the airflow about the aft-fuselage. In addition, the finlets generate an induced secondary vortex having an opposite rotation direction relative to the rotation direction of the vortices generated by the aft-fuselage, thereby counteracting the vortices generated by the aft-fuselage.

An aftertreatment system for treating constituents of an exhaust gas produced by an engine, comprising: a housing; a selective catalytic reduction (SCR) system disposed within the housing; a reductant injector disposed on a sidewall of the housing upstream of the SCR system and configured to insert a reductant into the exhaust gas; and a vortex generator disposed in the housing, the vortex generator comprising at least one deflector disposed on a surface within the housing, the at least one deflector configured to generate vortices in a portion of the exhaust gas flow flowing over the at least one deflector such that the portion of the exhaust gas remains attached to the surface at a downstream location of the surface.

A flow control device includes a cylindrical body disposed about a primary axis. The cylindrical body includes a primary flow passage extending therethrough. A ball element having an inlet flow passage extending therethrough is pivotable relative to the cylindrical body between an open position and a closed position. In the open position, the inlet flow passage is in fluid communication with the primary flow passage, and in the closed position, the inlet flow passage is not in fluid communication with the primary flow passage. The flow control device further comprises an internal flow control body having a collar positioned within the cylindrical body about the primary axis. A plurality of outer helical fins extend outwardly from the collar and define a plurality of outer helical passageways, and a plurality of inner helical fins are positioned inwardly from the collar and define a plurality of inner helical passageways.

A vortex ring generation device includes a casing having a discharge port, an extrusion mechanism, and a component supply port. The extrusion mechanism extrudes air in an air passage inside the casing such that the air is discharged, in a vortex ring shape, from the discharge port. The component supply port surrounds the air passage. A total circumferential length of the component supply port is or more of a total circumferential length of the discharge port. The extrusion mechanism includes a vibration plate and a drive unit that vibrates the vibration plate. The air passage includes a first passage, and a throttle passage continuous with a downstream end of the first passage. A component chamber is provided inside the casing. The component chamber contains a discharge component to be supplied to the component supply port. The component supply port is located downstream of the throttle passage.

A vortex ring generation device includes a casing having a gas passage and a discharge port, and an extrusion mechanism that extrudes a gas in the gas passage such that the gas in a vortex ring shape is discharged from the discharge port. V (m.sup.3) represents an extrusion volume, D (m) represents a diameter of the discharge port, L (m) represents a length of a cylinder having the diameter D and the volume V, and Re represents a Reynolds number of the discharged gas. 500Re3000 and 0.5L/D2.0.

A vortex ring generation device includes a casing having a gas passage and a discharge port, and an extrusion mechanism that extrudes a gas in the gas passage such that the gas in a vortex ring shape is discharged from the discharge port. V (m.sup.3) represents an extrusion volume, D (m) represents a diameter of the discharge port, L (m) represents a length of a cylinder having the diameter D and the volume V, and Re represents a Reynolds number of the discharged gas. 500Re3000 and 0.5L/D2.0.

An annular duct arrangement configured to cause a flow stream passing through the annular duct arrangement to be expelled from an outlet of the annular duct arrangement in a predetermined flow form.

A method for active flow control of a fluid flow that flows along a flow surface includes generating a first local velocity field in the fluid flow by introducing a first vortex structure into the fluid flow by a first flow control actuator coupled to a first actuation site of the flow surface, and introducing a second vortex structure into the first local velocity field by a second flow control actuator coupled to a second actuation site of the flow surface located downstream of the first actuation site, when a head vortex of the first vortex structure has propagated with the fluid flow downstream the second actuation site.