US2869773A

US2869773A - Bladed wheels of fabricated construction

Info

Publication number: US2869773A
Application number: US464066A
Authority: US
Inventors: Edward A Stalker
Original assignee: Stalker Development Co
Current assignee: Stalker Development Co
Priority date: 1954-10-22
Filing date: 1954-10-22
Publication date: 1959-01-20
Anticipated expiration: 1976-01-20

Description

2 Sheets-Sheet 1 Jan. 20, 1959 E, A. STALKER BLADED WHEELS OF FABRICATED CONSTRUCTION Filed Oct. 22, 1954 v? INVENTOR.

qm W 5 H E. A. STALKER BLADEID WHEELS OF FABRICATED CONSTRUCTION Jan. 20, 1959 2 Sheets-Sheet 2 INVENTOR.

Filed Oct. 22, 1954 speeds of about 400 feet per second or more.

United States Patent BLADED WHEELS OF FABRICATED CONSTRUCTION Edward A. Stalker, Bay City, Mich., assignor to The Stalker Development Company, Bay City, Micln, a corporation of Michigan Application October 22, 1954, Serial No. 464,066

4 Claims. (Cl. 230-134) This invention relates to compressors, turbines and the like and particularly to the bladed wheels thereof.

An object of this invention is to provide a bladed wheel assembly of light and economical construction. Another object is to provide a bladed wheel of sheet metal construction.

Other objects will appear from the description, drawings and claims.

The above objects are accomplished by the means illustrated in the accompanying drawings in which- Fig. l is a fragmentary axial section through a compressor incorporating a compressor wheel according to this invention;

Fig. 2 is a rear axial view of a wheel of the compressor of Fig. l partly in section;

Fig. 3 is a fragmentary section of a: wheel on line 3-3 in Fig. 2;

Fig. 4 is a fragmentary section on line 4-4 in Fig.

Fig. 5 is a fragmentary section of the disk and rim joints;

Fig. 6 is a fragmentary section through a spacer on line 6-6 in'Fig. 1;

Fig. 7 is a front axial view of a fragment of a spacer;

Fig. 8 shows fragments of two, spacer tubes, in registerihg relation;

Fig. 9 is an axial section at the rim of the first wheel at a through bolt; and

Fig. 10 is an axial section at the rim of the first wheel and between the through bolts. This invention includes compressor wheels for increasing the static pressure and density of an elastic fluid. In order to achieve a significant change in density with an axial flow compressor each wheel must be operated at a speed high enough to effect a significant change in. density, that is a change which in magnitude is outside the usual order of engineering accuracy in industry. Thus machines are considered to be compressors as distinguished from fans or blowers at tip At such a speed the average change in density along the blade length is about 3% which is just about the common order of accuracy of measurement of the density. Such compressors are expected also to operate at blade tip speeds close to the velocity of sound. At such speeds the change in pressure may be more than 70% or more than 10 pounds per square inch for air inducted at atmospheric pressure.

Since in compressor and turbine wheels there are substantial pressure variations from front to rear of eachwheel the ratio of the hub radius to the blade-tip radius is relatively large of a value of the order of 0.5 t and preferably greater so that the pressure difference between front and rear sides can be sustained without a return flow at the hub such as occurs in a fan. For the same reason the blades are spaced peripherally close together, preferably about one chord length or less apart.

Commonly half to all the pressure change occurs in the rotor between the leading and trailing edges. To sustain such a change in pressure along the rotor passages from leading to trailing edges of the blades the hub rim between adjacent blades and from leading to trailing edges is a fair and continuous surface. Also at all rotative speeds the case must fit closely about the blade tips which are contoured to the cylindrical surface of the case along substantially the whole length of the blade chord.

To diffuse the flow between blades to achieve a pressure change the flow should follow the blade surfaces without eddies. Accordingly the blades should have rounded leading edges. They should have sharpened trailing edges to be eificient.

Because of the limited weights of the blades and the rim means the disk of a compressor wheel can have a limited thickness of the order of 0.003 times the wheel maximum diameter (tip diameter) or less. Thus rather large disks can have a thickness less than 0.050 of an inch. These would be costly and diflicult to machine. The blades and rim means may have wall thicknesses less than the disk thickness.

It is commonly understood in engineering and industry that sheet metal construction is limited to sheets whose planer dimensions are large in comparison to their thicknesses for thicknessesless than about *3 of an inch. Sheets of greater thickness are called plates. (Steel sheet and plate manufacturers list their product of large planer dimensions of di or less as sheets and greater thicknesses as plates.) Sheet metal constructions are comprised of parts which are cut out from sheet material and require cutting which is limited chiefly to defining the contours of the part in the plane of the sheet, or to such parts which are subsequently given another shape by pressing with a die.

Referring now to the drawings thewheel assembly is indicated generally as 10. It comprises the wheels 12-15, the torque transmitting members or end disks 20 and 21, and the

shafts

24 and 26 for mounting the wheel assembly for rotationabout the axes of the shafts. The torque transmitting members; have portions fixed to the disk by suitable fastening means to be described.

Since the wheels are substantially alike, the front wheel will be described in detail and this will sufiice for the other wheels.

As shown particularly in Figs. 14 the wheel 12 is comprised of the wheel disk 30, the rim means 32, and the blades 34.

Each blade comprises the blade skin 40 fixed preferably by fused metal to the stem 42 which is made up of the front part 44 and the rear part 46. The front part has the flange 48 faying the rim means and fixed thereto pref erably by fused metal while the rear part has the flange 52 fixed similarly to the rim means.

The rim means is made of two

parts

56 and 58 which are joined over the flanges 60 of the disk 30 and to them by fused metal preferably solder.

Rim portions

56 and 58 have flanges 57 and 59 respectively at their radially inner ends, except on the outer sides of the wheel assembly, which extend axially in overlapping relation with the outer walls and the fixed vanes 100.

The wheels are supported in series between the end disks 20 and 21 by the bolts 74 which pass through tubes '76 (Figs. 1, and 68) and the disks 30. The. tubes are fixed between the outer wall 80 and the inner walls 82 by fused metal. The tubes 76 are recessed at one end to receive the tapered end of the adjacent tube 76'. See Figs. 1 and 8. Outer walls 80 extend axially between adjacent disks 30 while two inner walls 82 are arranged end to end with The other tubes are formed similarly.

3 abutting flanges 83, such inner and outer walls thus forming spacers between disks 30.

The ends of the spacers are formed as illustrated in Figs. 7, .9 ,and 10.. A ring 0 fits into each end on the inside surface .of wall 80 to which it is fixed by fused metal. The radial flange 91 of 9.0 fays a radial flange 92 of the wall 82. The flange 91 has a plurality of holes therein .to pass thebolts 74. The assembly thus provided, including the spacers, the tubes fixed to the outer and

inner walls

80 and 82, and the boits 74 passing through end disks 20 and 21, serves to transmit the torque irornone wheel to the next.

' The outer surface of the wall 80 abuts the flanges of the stator ring 100. j

The wheels and the spacers are readily fabricated of vpressingsiand parts of sheet metal, which may be soldered together. This avoids expensive machining and leads to a low cost assembly. j

The parts are preferably spot-welded together and sub- :sequently soldered in a furnace. Once the dies and tools are produced low cost labor can assemble the parts.

driving the wheel assembly through the bolts and spacers positioned at the rims of the wheel the disks do not need stiifeners for acting against axial loads and the structure has a very low weight.

"It Will thus be clear that the wheel assembly presents the great advantages of low Weight and cost.

While Ihave illustrated specific forms of the invention, his to Elie understood that variations may be made therein and that I intend to claim my invention broadly as indicated by the appended claims.

' I claim:

1. In combination in an axial flow rotor assembly compri singat least two rotor wheels spaced axially, each wheel comprising a sheet metal disk, a plurality of peripherally {spaced axial flow blades carried on said disk and projecting outward therefrom with rotor flow passages between said blades for conducting an elastic fluid, said blades being rotatable with said disk at blade tip speeds greater than .400 feet per second developing substantial changes in density and pressure in said fluid flowing through said rotor passages, a rim means of sheet metal construction extending between said blades and from front to rear thereof to sustain said changes in pressure and density, said rim means having a radially inward extending iflange, hollow annular spacer means of sheet metal construction positioned between adjacent said wheels, said spacer means including inner and outer generally cylindrical sheet metal walls both extending from one wheel disk to the adjacent such disk, a torque transmitting rnen1- her having portions thereof adjacent and fixed to said Walls, and fastening means extending in the general axial direction into said portions and said wheels and through said spacer means fixing said wheels and spacer means together for the transmission of torque from one to the other, said rim flange bearing on said spacer means.

2. In combination in an axial flow compressor rotor assembly, at least two rotor wheels in axial tandem relation, each said wheel comprising a sheet metal dish, a plurality of peripherally spaced axial flow blades carried on said disk and projecting outward therefrom with rotor flow passage between said blades for conducting an elastic fluid, said blades being rotatable with said disk at blade tip speeds greater than 400 feet per second developing substantial changes in density and pressure in said fluid flowing through said rotor passages and developing centrifugal loads at the inner ends of said blades, said disk having a thickness less than 0.003 times the maximum.

diameter of said wheel for sustaining said centrifugal loads, a rim means of sheet metal construction extending between said blades and from front to rear thereof to sustain said changes in pressure and density, said rim means having a radially inward extending flange, hollow annular spacer means of sheet metal construction positioned between adjacent said wheels, said spacer means including generally cylindrical sheet metal walls substantially coextensive with each other and extending between adjacent said wheel disks, a torque transmitting member having portions thereof adjacent to said rim means, and bolt means extending in the general axial direction into said portions and said wheels and through said spacer means fixing said wheels and spacer together for the trans mission of torque from one to the other, said rim flange bearing on said spacer means.

3. in combination in an axial flow compressor rotor assembly, at least two rotor wheels in axial tandem relation, each said wheel comprising a sheet metal disk, a plurality of peripherally spaced axial flow blades carried on said disk and projecting outward therefrom with rotor flow passage between said blades for conducting an elastic fluid, said blades being rotatable with said disk at blade tip speeds greater than 400 feet per second developing substantial changes in density and pressure in said fluid flowing through said rotor passages, said blades being of hollow sheet metal construction of light weight developing limited centrifugal loads at the inner ends of said blades, said disk having a thickness less than 0.003 times the maximum diameter of said wheel for sustaining said centrifugal loads, a rim means of sheet metal construction extending between said blades and from front to rear thereof to sustain said changes in pressure and density, said rim means having a radially inward extending flange, each said blade including a blade skin and a stern, said stern having a flange at the side thereof extending axially to said flange of said rim means and being fixed thereto for the support thereof, hollow annular spacer means of sheet metal construction positioned between adjacent said wheels, said spacer means including generally cylindrical sheet metal walls substantially coextensive with each other and with the space between adjacent wheel. disks, torque transmitting members in the form of tubes positioned between and secured to both said walls adjacent to said rim means, and bolt means extending in the general axial direction through said tubes and said wheels fixing said wheels and spacer means together for the transmission of torque from one to the other.

4. in combination in an axial flow rotor assembly, a rotor wheel comprising a sheet metal disk, a plurality of peripherally spaced axially flow blades each including a blade skin and an internal stem extending radially inwardly of said skin, means for fixing said stems to said disk in peripherally spaced relation thereon with said blades projecting outwardly therefrom defining flow passages between the blades for conducting an elastic fluid, a rim means of sheet metal construction extending between said blades and from front to rear thereof to sustain changes inpressure and density, said rim means having a radially inwardly extending flange faying the inner portion of said stern means, and means for bonding the flange of saidrim means to said stem portions to fix said rim means in assembled position thereon.

References Cited in the file of this patent