Vortex generator with sub-aperture and method of manufacturing the same

A method of manufacturing a vortex generator for flow of a fluid comprising:

• simultaneously molding a housing and a valve in a molding die, wherein:
• the housing includes a passage through which the fluid flows, the passage having an axis;
• the valve is movably coupled to the housing between a fully closed position and a fully open position for changing flow of the fluid in the passage, wherein the valve includes an open portion that defines a main aperture for generating a vortex in the flow of the fluid, and wherein the valve also has an intermediate position between the fully closed position and the fully open position;
• the housing further includes a recessed portion such that the recessed portion of the housing and the valve cooperate to define a sub-aperture through which the fluid flows when the valve is positioned in the intermediate position;
• and
• the molding die is moved in a direction approximately parallel to the axis of the passage to remove the housing and the valve from the molding die.