US2441239A - Blower apparatus - Google Patents

Description

I w. B. FLANDERS 2,441,239

BLOWER APPARATUS Filed Jan. 29, 1944 2 Sheets-Sheet l INVENTOR WARREN B.F1 ANoERs.

ATTORNEY W. B. FLANDERS BLOWER APPARATUS ay H, 1948.

Filed Jan. 29, 1944 2 Sheets-Sheet 2 MNDWWMMQ VOLUME Fzchii.

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INVENTOR WARREN B.FLAN DER$.

WITNESSES:

ATTORN EY Patented May ll, 1948 UNITED i STATES PATENT ()FFICE I I BLOWER APPARATUS Warren B. Flanders, Philadelphia, Pa., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa. a corporation of Pennsylvania Application January 29, 19 44, Serial-No. 520,165

fluid initially flows generally in an axial direction,

it has. been found that, as the discharge opening is decreased at constant speed, the pressure will rise to a certain point, will then fall-from three to thirty per cent depending upon the design, and then-will rise until the discharge opening is entirel'y closed. During the range of falling. pressure, or dip," the flow of fluid, for example, air,

becomes somewhat erratic and a tendency to centrifugal action becomes apparent. When this centrifugal action overcomes the propelling action at the tips of the-vanes or blades, back flow starts; however, until such time as back flow-becomes deflnitely established, an unstable condition of operation is encountered, the fluid pressure fluctuating to an undesired extent in many cases.

This problem and a solution therefor is fully discussed in my prior Patent No. 2,169,232, granted to Westinghouse Electric 8: Manufacturing Company on August 15, 1939. In this patent, it is proposed to provide an annularv vane or wall means, associated with the propeller blades or vanes, for obstructing recirculation: The prescirculation or back flow of fluid is deterred or prevented without the necessity of adding annular wall structure as called for by the above-menv tioned patent.

Yet another object of the invention is the. provision, in pump or blower structure, of a plurality of propeller blades or vanes having tip edges which are substantially parallel to their axis of rotation throughout at least a maior portion of their length, together with an annular casing structure enclosing the propeller blades and having clearance with respect to the tip ends thereof, which clearance increases in the direction of fluid I flowpast the blades.

A further object of the invention is to provide, in a pump or blower structure having a plurality of propeller blades whose tip edges diverge with 3Ciaims. (Cl. 230-120) respect to their axis of rotation in the direction of fluid flow therepast, a housing structure there- 'ifor having clearance with respectto'the blade tip edges which is substantially uniform through- -out the length of the blades.

Another object of the invention is to provide.

in pump or blower apparatus, apropeller structure having a plurality of blades disposed within a casing structure, the propeller blades and the 10 casing structure cooperating to provide passages for flow of fluid therepast, which passages are. of

increasing cross-sectional area from theiriniet edges to their outlet edges. I

These and other obiects are eifected by the invention as will. beapparent from the following e description and claims taken in connection with the accompanying drawings, forming a part of this application. in which: t

Fig. 1 is a vertical sectional view of a propeller blower incorporating the subject matteroi the present invention:

Fig. 2 is a similar view showing a modifled construction, a portion thereof being broken away;

Fig. '3 is a. diagram applicable to a propeller blower not provided with the ment; and, I

Fig. 4 is a similar diagram, illustrating the im proved performance obtained by use of the present invention.

presen} improvepropeller, not provided with any means for pre venting recirculation, has flow conditions as indicated by the'curve of Fig. 3 to the right of point -A when the blower is operated with a volume I greater than that of point A, and tothe left of point B when the volume is. less than that of point B. Between the points A and B, pulsations occur as the flow condition changes from that in a general axial direction to a condition of back' flow 40 or recirculation. The portion-oi the curve to the right of A covers stable operation where the axial component predominates over'the radial component, the latter component being due to centhe radial component predominates: however, in the transition-range between these-points, the unstable or pulsating condition arises.

Theunstable condition arising because of the I centrifugal action at the blade or vane tips, ap-

,plies not only to propeller pumps or blowers, such as herein illustrated, but also to pumps or blowers having combined propeller and centrifucal characteristics.

The fluid flow through a conventional a... of

trifugal force, and the portion 'of the curve to the left of 3 corresponds to stable operation where Referring now to the drawings more in detail,

. 3 there is illustrated, in Fig. 1, a propeller blower ll, having a casing structure providing an annular passage I l for flow of fluid. This passage I I may be said to comprise a converging inlet portion l2 and a diverging outlet portion ll. joined by an intermediate portion H. The inlet portion I2 is defined by the inner wall 15 and the outer wall 16, the intermediate portion I4 is comprised by the propeller hub l1 and the outer wall it, while the outlet portion 13 is defined by the fairing member I9 and the outer wall structure 20. Preferably, the outer wall 20 is provided with a flange 2| by which the entire structure may be secured to and supported from any suitable supporting structure, for example, the deck of a vessel.

The fairing member I! is supported from the outer casing member 20 by discharge guide vanes 22 and houses a bearing (not shown) for the lower end of the propeller shaft 23, on which the propeller hub 11 is secured. Preferably, the upper end of the shaft 23 is likewise supported by a bearing (not shown) and is driven by suitable means, such as a motor or a turbine. the latter being supported by the casing structure, indicated in its entirety at 25. Inasmuch as the means for rotating the shaft 23 forms no part of the present invention, further description thereof is omitted for the sake of brevity.

The propeller hub l1 carries a plurality of propeller blades or vanes 26 which, in the construction illustrated in Fig. 1, have tip edges 21 which are substantially parallel to the axis of rotation of the shaft 23. The outer casing I! of the intermediate portion H of the annular passage H is disposed in close proximity to the blade tip edges 21 adjacent'their inlet edges and diverges therefrom to provide a gradually increasing clearance 28 between the casing and blade tips in the direction of fluid flow through the annular passage. It

, will be'apparent that this increased clearance 28 provides space for the centrifugal component of flow of fluid through the intermediate portion of the passage, thereby deterring any tendency of the fluid to back flow toward the inlet of the intermediate portion.

In Fig. 2 is illustrated a modification of the construction just described, in which the tip edges of the blades 50, as well as the outer casing 18, diverge in the direction of fluid flow. While the clearance at between the blade tip edges and the casing 18, is substantially constant throughout the length of the blade tip edges, nevertheless, there is provided added space into which the centrifugal component of flow of fluid through the propeller structure may move, thereby avoiding any tendency of back flow toward the inlet to the intermediate portion of the annular passage.

While the invention has been shown in several forms, it will be obvious to those skilled in the art that it is not so limited, but is susceptible of various other changes and modifications without departing from the spirit thereof, and it is desired, therefore, that only such limitations shall be placed thereupon as are specifically set forth in the appended claims.

What is claimed is:

1. Fluid propulsion apparatus including a propeller having a hub and a plurality of blades; casing and hub structure cooperating with the blades to define between the latter passages for flow of fluid; and means for deterring back flow of fluid in said passages, said means comprising the formation of the casing structure in diverging relation with respect to the tips of the blades from the region of their inlet edges to the region of their outlet edges.

2. In fluid translating apparatus, a double walled casing providing an annular passage for a shaft extending axially of the annular passage;

and a propeller including a hub secured to the shaft and a plurality of blades carried by the hub and disposed within the intermediate portion of the annular passage, said blades having tip edges lying in planes substantially parallel to the axis of rotation of the propeller, and the outer wall of the intermediate portion of the annular passage diverging from the tip edges of the propeller blades in the direction of fluid flow to deter back flow of fluid in the region of said propeller blades.

3. In fluid translating apparatus, a doublewalled casing providing an annular passage for flow of fluid, said passage comprising inlet and outlet'portions joined by an intermediate portion; a shaft extending axially of the annular passage; and a propeller including a hub secured to the shaft and a plurality of blades carried by the hub and located in the intermediate portion of the annular passage, said blades having tip edges which are substantially parallel to their axis of rotation throughout a major portion of their length, and the blade tip edges having clearance with respect to the adjacent outer wall of the an- .nuiar passage intermediate portion, said clearance increasing in the direction of fluid flow.

WARREN B. FLANDERS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS FOREIGN PATENTS Country Date Great Britain Mar. 3, 1932 Number Number

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