US1993158A - Air moving apparatus - Google Patents

Description

March 5, 1935. M. FUNK 1,993,158

AIR MOVING APPARATUS Fi'led Sept. 8, 1930 2 Sheets-Sheet 1 IN V EN TOR.

1 ATTORNEY March 5,1935. JFUNK 1,993,15s-

AIR MOVING APPARATUS -Filed se Ls, 1950 I 2 Sheets-Sheet 2 IIiVgENTOR. waWe M A TTORNEYS.

Patented Mar. 5, 1935 PATENT OFFICE 1,99s,15s AIR MovnmI APPARATUS James M. Funk, Rockford, Ill., assignorto George D. Roper Corporation- Application September 8,1930, Serial No. 480,422

8 Claims.

the upstream diameter being greater than the propeller diameter, and the center of lift of the aerofoil at the propellers tip being forward of the entering edge of the shroud.

One application of the invention is illustrated in the accompanying drawings wherein the principle involved is shown in connection with a heater. It should be clearly understood, however, that this adaptation is merely illustrative and must not be construed as a limitation of the uses to which the invention" can be put.

In said drawings: Y

Fig. 1 is a view in rear elevation of a hot water heat radiator equipped with. the invention;

Fig. 2 is a view in vertical section, taken on the line 2-2, Fig. 1;

Fig. 3 is a detail view in cross-section of an aerofoil member which has been selected as an aid in describing the principle of operation of the invention, and r Fig. 4 is a diagrammatic drawing showing inflow and outflow air currents and the novel effect secured with the shroud of my invention,

. whereby the air handling facility of the air screw propeller is greatly increased.

In my Patent Number 1,327,543, issued January 6, 1920, I have shown how it is possible to increase the air handling facilities of an aeroplane propeller by the use of a shroud structure used in combination with certain controlling elements.

- From actual experiments and tests made it has been proven that a propeller, fan or the like when given the benefits of a properly designed shroud structure will function to far better advantage and this is true when the propeller is used, as such or when it becomes a fan or blower.

In my patent above identified I have shown a so called variable pitch shroud located in a certain predetermined relation to the propeller. In the present invention the location of the shroud with respect to the propeller is changed so as to cut ofi parasitic currents whose bad effect upon performance was not realized in the previous central opening substantially corresponding to construction and consequently were not baifled as they are in the present structure. Furthermore, in accordance with the present invention, the variable characteristics of the shroud are discarded in favor of a rigid non-adjustable con- 5 struction which adapts it better to use with fans, blowers and the like, although it is still well adapted to use with propellers on'aeroplanes.

Referring now to the drawings in detail, 5 represents a four bladed air screw pr peller of 10 a'tvp cent, designed for use in connection with he. anc.....crs such as hot water heat radiators'. According to the present showing the fan 5 is mounted by its hub 6 direct to the shaft '7 of an electric motor 8. The base9 of the air 15 screw propellers motor is supported upon a pedestal like structure 10 which includes a downwardly depending arm 11 and a cross rod 12. The lower end of the arm 11 and opposite ends of the cross rod 12 are bolted or otherwise fastened to the housing 13 for the radiator core 14. The housing 13 may be stamped from sheet metal or constructed in any other way suitable for the purpose. In any event it will be made with a the diameter of the propeller fan. In thepresent instance it is of four corner design having rearwardly extending surrounding walls of a depth to hold the radiator core 14 in proper spaced re?- lation in front of the propeller.

With such a heater assembly rotation of the fan 5 will force air through the radiator core 14 and with hot water or other heat medium circulating through the core sections a hot air blast will be realized'in front of the heater.

It isth'e purpose of my invention to increase the air handling facility of the air screw propeller 5 as previously mentioned and I propose to accomplish this objective primarily with the aid of a fixed shroud structure represented as at 14'. 40 The same being preferably constructed of pressed sheet metal and disposed in the central opening in the front of the housing 13 surrounding the fan blades 5'. The form and proportioning'of the shroud 14', as well-asits particular relationship to the propeller -5 are. most important. First of all, it will be observed that it is circular in form and concentric with the propeller 5, the tips of the propeller blades being disposed in close proxir'hity to the inside of the shroud (see Fig. 2). Next, it will be observed that the shroud-is of tapered or funnel shape with the trailing edge relation to the entering and trailing edges of the shroud is also important; the center of lift of the aerofoil at the tips of the blades is forward of the entering edge of the shroud. In other words, the

shroud is conformed to the propeller to provide at the propellers tips being forward of the entering edge of the shroud. The propeller 5, being an air screw propeller, is properly referred to as an aerofoil, as those skilled in the art are well aware, and the design of the shroud is based from start to finish on the presumption that the part 5 is an air screw propeller, inasmuch as an ordinary fan, as that term is generally taken to imply, will not give the results which this invention was designed to produce. Regardless of the characteristics of each particular propeller, the above statement as to the form and relationship of the shroud to the propeller applies, but it will be understood that a specific shroud angle, shroud trailing diameter and distance of termination downstream from the trailing edge of the propeller is demanded for each change in geometrical proportions of the propeller, these angles, diameters and distances being figured mathematically in relation to the propeller for which the particular shroud is being designed.

Referring now to Fig. 4, I shall explain by reference to this diagram the actual performance of the shroud 14 and that portion of the shroud referred to as the nosing 16. In this view, the arrows indicate air streams and are shown on a line corresponding with the distance in front of the propeller equal to .125 times the diameter and a distance behind the propeller equal to .0625 times the diameter, as well as in the immediate vicinity and around the periphery of the propeller. The air streams, with which this invention is most concerned, are .those marked A, T, 1, 2, and 3. The angle of these arrows and their length indicate the direction of the flow in relation to the propeller disc and the relative velocities. The arrow T indicates air drawn or pulled in by the propeller through the lateral tips and commonly referred to as the radial flow. The other arrows at right angles to the propeller are commonly referred to as the axial flow. It will be noticed that arrows 1, 2 and 3 are pointed in counter-flow and that they are the termination of streams originating in front of the propeller. This is due to the fact that the propeller, as illustrated in Fig. 3, being an aerofoil, produces a positive pressure under the blade and a negative pressure on tie upper surface of the blade and at the lateral tip the air thus put under pressure flows -around the tip into the lower pressure area above the blade, thus producing a turbulence, as

' is illustrated by the arrows and dotted lines.

In Fig. 8, the aerofoil is numbered 5 to correspqnd to the propeller. At 20, are indicated the air streams striking the face 21 of the propeller and deflected therefrom in an area of positive pressure. The streams 1'7 striking the edge 18 are divided, part. going into the pressure area, and the rest into the negative pressure area on the back of the blade. The shroud of my invention deals with the turbulence and prevents the wall of the housing.

eter than the disc swept out by the propeller blades. The exact position of the propeller with parasitic air streams numbered 1, 2 and 3, from returning into the propeller tip. The area between the tips of the propeller and the shroud is under suction, the suction being produced by the action of the propeller as illustrated in Fig. 3. This suction manifests itself by bending the line A and line T at the nosing 16 in the manner shown, which means that more air is drawn in and is handled by the propeller without increasing the horsepower absorbed. The air indicated by lines 1, 2, and 3 are velocity pressures translated into static pressure by impact with the inside of the back wall of the housing 13 or for the sake of this illustration the part numbered 15 in Fig. 4, it being obvious that the portion 15 is, to all intents and purposes, a part of the rear The static pressure thus developed results in the movement of air through the four corners of the core 14. In other words, the area of the propellers effective outflow is actually greater than the diameter of the propeller. The line T should now be noted because it is most important in regard to the nosing 16, according to the principle laid down by Otto Lillienthal on the forward and upper surface of an aerofoil, a partial vacuum or lower pressure is produced by the phenomena of air motion. This suction on the upper surface has the effect of increasing the magnitude of the air streams indicated by line T. Increasing line T means an increase in the mass of air moved through the propeller pressure in the outflowing stream. The importance of this in the case of a heater such as that herein shown can be easily appreciated. In the case of an aeroplane, it means an increase in thrust so that the aeroplane gets off in a shorter run. In conclusion, therefore, it will be seen that the shroud not only converts what would otherwise be parasitic reactions to beneficial results, that is, by the baflling of currents 1, 2, and 3, but also draws in more air by reason of the action of the nosing 16, that is, by increasing streams A and T.

Another feature which is of importance so far as the present heater is concerned resides in the novel stream-line design of the core sections 25. A core section designed as shown will function with two advantageous results. First, the air lines will completely'embrace and scrub the entire surface area ofthe sections and from end to end and as a result more air will contact with the sections-and thus create a. more effective heat transfer. Furthermore, the hot water, steam, or gases circulating through a stream-line core section will be spread out in such a manner as to present maximum area for radiation purposes.

The design selected for illustrating the invention is especially adapted for unit heaters and coolers but as previously stated this illustration is not to be taken as a cation of the invention as it will also find a good field of usefulness in othgil'1 air handling apparatus, of which the most portant worth mentioning are propellers for aeroplanes.

limitation of the applidisc and in consequence increases the Having thus described and shown an embodiment of this invention, what I claim and desire angle to the axis of rotation of the blades and face at an angle to the" axisof rotation thereof terminating in a trailing edge of less diameter than the disc swept out by the blades, the leading annular edge of said shroud structure being of greater diameter than the aforesaid disc and having a curved nose portion so situated with respect to the propeller to serve as an aerofoil for causing radial inflow to the tips of the blades.

2. An air moving apparatus comprising in combination, an air screw propeller havinga plurality of rotatable blades, and a continuous annular shroud structure fixedly mounted with its inner surface arranged to extend across the tips of the blades at an oblique angle to the axis of rotation of the blades and terminating be-' yond the trailing edges thereof in a diameter slightly less than the propeller diameter, the lead ing annular edge of said shroud structure being disposed in the plane of the center of the propeller's lateral tips and of a diameter slightly larger than that of the propeller.

3. An air moving apparatus comprising in combination, an air screw propeller having a plurality of rotatable blades, and a shroud structure surrounding said blades with its inner surand extending across the tips of the blades, originating in a curved nose at its leading edge of a diameter greater than that of the propeller and with a trailing edge of less diameter than that of the propeller, said curved nose being disposed in the plane of the center of the propellers lateral tips, and being so formed whereby the same serves as an aerofoil for causing radial inflow to the tips of the blades.

4. An air moving apparatus comprising, in combination with the wall of a housing having a central opening provided therein, an air screw propeller having a plurality of rotatable blades, and a shroud structure surrounding said blades having the inner surface thereof at an angle to the axis ofrotation thereof, the shroud originating in a curved nose at its leading edge and with a trailing edge of less diameter than the diameter of the disc swept out by the rotation of the blades, said shroud having its leading edge provided with the rounded nose projecting from the wall of the housing and of a diameter greater than that of the propeller, said nose portion being so disposed with respect to the propeller to serve as an aerofoil for causing radial inflow of air to the tips. of the blades.

5. In an air handling device, the combination of an air screw propeller of a certain diameter and an annulus surrounding only the disc swept 55 out by the propeller, said annulus being in close nInm-n- A a m proximity to the tips of the blades oisaid pro-' peller, said annulus being formed to provide an evase discharge and venturi in the downstream area of less diameter than that of the propeller, and being formed to provide a projected angle aero'foil in the upstream area of greater diameter than that of the propeller, said annulus being so disposed that the leading edge is in the same plane with the center of the lateral tips of the blades of said propeller.

6. An air moving apparatus .comprising in combination, an air screw propeller having a plurality of rotatable blades, and an annular shroud structure having an inner surface providing a working face extending across the tips of the blades at an oblique angle to the axis of rotation of the blades, said shroud having its leading edge of greater diameter than the disc swept out by the blades and terminating in, a trailing edge of less diameter than the diameter of the disc swept out by the rotation of the blades, the leading annular edge of said shroud structure being disposed in the plane of the center of the propellers lateral tips.

7. An air handling apparatus comprising, a housing through which air is to be passed, an air screw propeller having a plurality of blades for propelling the air through said housing,. an end plate for said housing having a central opening in which said blades revolve, and anannular shroud for said blades in said opening and having an inner surface extending across the tips of the blades at an oblique angle to the axis of rotation of the blades, the shroud terminating in trailing relation to the propeller in a diameter less than that of the propeller, the entering edge of said shroud being of a greater diameter than that of the propeller and disposed in the same plane with the center of the lateral tips of the blades of said propeller.

8. An air moving apparatus comprising in combination, an air screw propeller having a plurality of rotatable blades, and a continuous annular shroud structure fixedly mounted with its inner'surface arranged to extend across the tips of the blades at an oblique angle to the axis of rotation of the blades and terminating beyond the trailing edges thereof in a diameter approximately nine-tenths of the propeller diameter, the leading annular edge of said shroud structure being disposed in the plane of the center of the propellers lateral tips and of a diameter approximately 1.2 times the propellers diameter.

- JAMES M. FUNK.

cenrrrlcnrn or CORRECTION Patent No. 1.993,l58. March 5. 1935.

JAMES M. FUNK It is hereby certified that the above numbered patent was erroneously issued to "George D. Roper Corporation"as assignee of the entire interest in said invention whereas said patent should have been issued to the inventor said "Funk" as shown by the records of the case in this office; and that the said Letters Patent should be read with this correction therein that. the same may conform to the record of the case in the Patent Office. I

Signed and scale this 18th day of June,- A. D. 1935.

Les I it: Frazer K Acting Commissioner of Patents.

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