Vortex generator for centrifugal fans



A centrifugal fan having a plurality of formed vortex generators fixed onto the outer wall of an annular member leading into the air inlet for the fan-wheel to cause mixing of the slower air discharged from the wheel and the skin friction air current created by the wheel.Get more news about Vortex Centrifugal Fan,you can vist our website!
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Centrifugal fans, of the type to which this invention relates, involve a fan-wheel rotatively mounted in a scroll-spiral type housing having an axial air-inlet and air-outlet in a plane parallel to the axis of rotation. The air flow is drawn in axially by the fan-wheel from the housing air-inlet and is discharged peripherally therefrom into the housing structure to effect an enlarging spiral flow to a housing air-outlet. Generally, the fan-wheel comprises a series of circumferentially-spaced, radially-extending blades fixed between a pair of axially spaced plates. An annular element spans the housing interior to connect the housing air-inlet with the fan-wheel air-inlet.
It is well known that there are two distinct types of air currents that tend to circulate around the inside of this spiral housing chamber. One of these air currents is close to the front or air-inlet plate of the fan wheel. This current is caused by the "skin" friction of this front plate dragging the air along with it. Because of the high velocity of the fan wheel rotation, this skin-friction-induced air current tends to concentrate adjacent the face of this front plate and over the smaller diameter of the air-inlet element and move at a speed much faster than the more distant portions of the air flow through the housing.
The aforementioned skin-friction-induced air current also supplies the air that feeds the recirculation occurring between the high pressure air in the fan housing and the lower pressure air coming through the annular air inlet. This leakage occurs between the smaller diameter air inlet of the fan wheel plate and the innermost edge of the annular air inlet. Some recirculation is deemed desireable in order to assure complete "filling" of the fan wheel blades.
The other type of air current is the lower velocity air being discharged from the rotating fan wheel blades. This is the primary air flow which is directed out of the fan outlet to achieve useful work.
Many attempts have been made to merge the two air streams efficiently and direct them out of the fan outlet while still feeding the necessary recirculation between the fan wheel and air inlet. Some of the attempts deal only with the recirculation, while others deal only with "skimming" the skin friction air and directing it out of the outlet.