US 2313413 A
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Description (OCR text may contain errors)
March 9, 1943.
J. R. WESKE AXIAL FLOW FAN Filed July 2, 1940 INVENTOR.
JOHN R. WESKE AT'roRNEYs.
Patented iiiar. 9, i943 OFFICE 2 FLOW FAN .lohn R` Weske, Hudson, Ohio Application July 2, 1940, serial No. 343,609
(ci. 23o-12o) 3 Claims.
The rotating as well as the stationary blades of axial ow fans produce a deflection of the :dow in circumferential direction in addition to the axial direction of ow through the wheel. Thus if iiow of air approaching the wheel is axial only, circular motion will be found to exist as well when the air leaves the wheel, such deection in circumferential direction being proportional to the torque acting on the shaft. High torque and consequential high power input results in a large deflection in .circumferential direction. ,Conventional blades do not permit of a high deflection, since the iiow separates over the back of the blades causing eddying and stalling.
The present improvements, relating as indicated to a fan of the axial ow type, have as their object to increase output as to quantity of air handled, pressure produced and ali: horsepower, as compared with conventional fans of this type. This is accomplished by a special arrangement of plural series of fan blades on the hub-or rotor, and at the same time by employing a similar unique arrangement of vanes stationarily mounted immediately beyond such rotating blades, not only is desired axial direction imparted to the air stream, but vortices at this point in the air stream where it -is thus straightened out are reduced or eliminated, thus doing away with a source of energy loss. A further object is to provide a fan which for a given capacity will reduce the fan noise below that of fans of conventional design, and thus overcome this drawback.
To the accomplishment of the foregoing and related ends, said invention, then, consists of the elements hereinafter fully described and particularly pointed out in the claims.
The annexed drawing and the following description set forth in detail certain structure embodying the invention, such; disclosed elements constituting, however, but one of various structural forms in which the principle of the invention may be used.
In said annexed drawing: Fig. i is a front elevational view of a fan embodyins my present improvements;
nFig.. 2 is a horizontal sectional view thereof taken on the plane indicated in line 2 2 of Fig. l; and
Fig. 3 is a sectional view at right angles to that of Fig. 1, showing certain details of the fan mounting.
As illustrated, the fan is shown as mounted in a cylindrical housing i which forms a duct through which the stream of air generated by the action of the fan is caused to pass in the direction indicated by the arrows, Fig. 2. Depending upon the use to be made of the fan, this duct may discharge into a chamber or be part of alonger duct such as a wind tunnel or'the like. The rectangular frame 2 in which the duct is shown as being supported is, of course, merely conventional, and this is also true of the drive 1o means shown as consisting of a belt 3 which passes around a. pulley l on the shaft 5 that carries the hub or rotor 8 of the fan proper. Such shaft is suitably journaled in a hub or stator l that is aligned with the rotor 6 and upported, as will be presently described, in the ousing l. Where the rotor and stator are of the diameter indicated relatively to that of the chamber or duct, they will preferably be of hollow construction as shown, the front end of the rotor being closed by a nose piece 8. f
Mounted on the hub or rotor 6', as previously indicated, are two or more series of fan blades IIJ arranged in a generally axial direction, successive blades of each series being slightly offset circumferentially with respect to the preceding blade. such series has an increased pitch over the preceding blade. The blades may be of airfoil shape in cross-section, as shown, or they may be simply curved blades of uniform thickness. The outer 'ends of the blades may be curved as shown in ing means of conventional type (notl shown) may be provided.
While the number of series of such blades Il as shown is the same as blades I'Il on the rotor of the fan, such number may be greater or smaller. However, these series of blades Il just as in the case of blades I0, are not only axially arranged but successive blades of each series are slightly offset circumferentially with respect to the preceding blade and are of increasing pitch. As shown in Fig. 2, both the direction of oisetting and inclination of the pitch of said blades or vanes Il are opposite from the direction ofl offsetting and inclination of blades l l will furthermore not necessarily, be of airfoilthe blades l0. Such preferably, although shape..
Furthermore, each successive blade in f In operation, the air is deflected only a part of v the desired amount by the foremost blades i@ on the rotor. The second blades of each series being slightly oiset circnmferentially with respect to such foremost blades, will operate in air that has not been in contact therewith, and so willl add tothe circumferential deection of the air.
This process will be repeated in succeeding blade rows until the desired deflection has been ac-v complished, it being understood that while only three such rows are shown in the fan as illustrated, the number may be varied as required.
Such arrangement of the blades i6 in rows or in that the speed of the fan for a given capacity islower than that of a conventional fan. This is of importance since such reduction of speed results in a. corresponding reduction in the noise of operation.
As previously noted, the stationary or guide vanes I l by virtue of their tandem arrangement,
permit reduction or elimination of vortices in' the space between the blades, with corresponding saving of energy expended. In other words, not onlyis the stream of air produced by the rotation of the fan proper` engaged and divided up into a.. series `oi axial streams by -the series of stationary varies, butv such air streams are in part further sub-divided and iiow through hetween successive vanes, materially assisting in breaking up the vortices which otherwise tend to form in the spaces between such series.
It should be remarked that quitefoiten, for instance, with fans that take air from a room, the casing will notl be strictly cylindrical but `have a converging, bell-mouth shape.. Likewise the hub may have a shape like that oi thenose of an airship, and both the bell-mouth and the streamlined nose may extend to the down-stream side of the runner or fan-wheel. It will accordingly be understood that the term "cylindrical" aeiaais as employed herein connotes such modied forms of casing and hub, since my improved construction of varies or blades may equally ,well applied-to casings and hubs of other shapes.
Other modes of applying the principle of my invention may be employed instead of the one explained, change being made as regards the mechanism herein disclosed, provided the means stated by any of vthe following claims or the equivalent of such stated means be employed.
I therefore particularly point out and distincte' ly claim as my invention:
1. The combination with a cylindrical duct, of a cylindrical rotor mounted centrally therein, and a plurality of series of axially arranged fan blades carried by said rotor, successive blades of each series slightly overlapping the one preceding, being slightly oiset circumferentially with respect to the preceding blade and being of increasing pitch as well.
2. The combination with a cylindrical duct, of a, cylindrical rotor mounted centrally therein, a cylindrical stator aligned with seid rotor, a. plurality of series of Vaxially arranged fan blades carriedby said rotor, and -a plurality of series oi similarly arranged venes carried by said stator, successive bla-des and vanes of each such series slightly overlapping the one preceding, being slightly oiset circumerentiallywith respect to the one preceding and being of increas ing pitch as well. A v
3. jhe combination with a. cylindrical duct, of a cylindrical rotor mounted centrally therein, a cylindrical stator aligned with said rotor, a plurality of series of axially arranged fan blades carried by said rotor, and a plurality of series of similarly arranged venes carried by said stator, successive blades and vanes of each such series slightly overlapping the one preceding, being slightly offset circumferentially with respect to the one preceding and being of increasing pitch as well, both the direction of offsetting and inclination of the pitchof the vanes carried by said statorbeing opposite from the direction of offsetting and inclination ci the pitch of the blades carried by said rotor.