US2415847A

US2415847A - Compressor apparatus

Info

Publication number: US2415847A
Application number: US486142A
Authority: US
Inventors: Arnold H Redding
Original assignee: Westinghouse Electric Corp
Current assignee: CBS Corp
Priority date: 1943-05-08
Filing date: 1943-05-08
Publication date: 1947-02-18
Anticipated expiration: 1964-02-18

Description

Feb. 18, 1947.

A. H. REDDING 2,415,847

COMPRESSOR APPARATUS Filed May 8, 1943 2 Sheets-Sheet 1 as H 5.

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INVENTOR Rmvou: H. REDDINQ.-

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ATTORNEY Feb. 18, 1947. REDDlNG 7 2,415,847

COMPRESSOR APPARATUS Filed May 8, 1943 2 Sheets-Sheet 2 Fig. 13. F'IG- 14.

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BY 1 w, ATTORNEY Patented Feb. 18, 1947 UNITED STATES PATENT OFFICE 2,415,847 COMPRESSOR APPARATUS Arnold H. Bedding, Swarthmore, Pa., asslgnor to WestinghouseElectric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application May 8, 1943, Serial No. 486,142

Claims. 1

This invention relates to axial-flow compressors or blowers and the like, and particularly to improved blading therefor and the method of making the same, and it has for an object to, provide an improved method and device of the character set forth.

It is also an object of the present invention to provide blading for apparatus of the character set forth which is relatively easy to manufacture.

Blading for high eiiiciency compressors has required complicated forging and machining operations which are time-consuming and require a high degree of skill. In accordance with the present invention, an airfoil blade is provided which is eflicient and requires but a few simple machining operations in its manufacture.

While the compressor and blading therefor to be hereinafter described is particularly adapted for use with and to be driven by a high-speed gas turbine, it will be apparent to those skilled in the art that the invention is not limited to this particular application.

These and other objects are effected by the invention as will be apparent from the following description and claims taken in connection with the accompanying drawings, forming a part of this application, in which:

Fig. l is a side elevational view of an axial-flow compressor incorporating the present invention, portions being broken away for the sake of clary;

Fig. 2 is a plan view of a portion of one of the rotors of the compressors shown in Fig. 1;

Fig. 3 is a sectional view taken substantially on the line III-III of Fig. 2;

Figs. 4, 5, 6, 7 and 8 are sectional views taken substantially along the lines IV-IV, VV, VIVI, VII-VII and VIII-VIII, respectively, of Fig. 3;

Fig. 9 is a fragmentary view showing a portion of one of the compressor rotor hubs and blades attached thereto;

Fig. 10 is a fragmentary view of a portion of one of the rows of stationary guide vanes of the coinpressor;

Figs. 11 and 12 are sectional views taken substantially on the lines XIXI and XII-XII, respectively, of Fig. 2, and drawn to a smaller scale;

Figs. 13, 14 and 15 are views, in perspective, of one of the blades of the compressor and showing schematically a jig on which the blade is mounted for finishing the convex surface thereof; and

Figs. 16 and 17 are views similar to Fig. 15, illustrating two modifications of the invention.

Referring to the drawings, the compressor, generally indicated I0, is of the rotary axial-flow type, It comprises an outer casing structure II in which is journaled a shaft I2 having one or more hubs or discs l3 carrying rows of rotor blades M which cooperate with intervening rows of stationary blades or vanes l5. Air entering the intake I6 is directed by the stationary guide vanes ll fixed to the casing for axial-bow compression in successive stages by the rows of blades and vanes l4 and I5.

The present invention is particularly suitable for use with a high-speed gas turbine power plant, such as employed in the propulsion of aircraft, and, consequently, must be of minimum weight while capable of operating safely at extremely high speeds which may be as high as 20,000 R. P. M. or higher. The improved compressor, while preserving high efficiency, employs rotor blades and stationary guide vanes which are of minimum weight and easily shaped without the use of elaborate jigs or complicated machining operations.

The rotor blades l4 have an integral root section IQ of rounded section, permitting the same to be anchored in complementary-shaped recesses 20 formed in the rotor hubs. The intermediate guide vanes l5, which are shaped like the rotor blades, are provided with integral tenons 2| at each end, secured in spaced holes provided in concentric split rings 22. These rings support the vanes and are in turn mounted in the casing H in a known manner.

The working portion of the rotor blades and of the guide vanes is substantially segmentshaped in cross section throughout its length. The rear face 23 of each blade, hereinafter referred to as the convex face, is substantially an element of a cylinder or a cone, which is preferably modified as hereinafter pointed out. The forward or leading face 24, hereinafter referred to as the chordal face, comprises a surface made up of chords of the cylinder.

To obtain high efficiency, it is desirable that the rotor blades be warped from root to tip to correct for the change in direction of flow and velocity of the air from the root to tip at the entering edge 25 of the moving blades. It is also desirable that the cross-sectional area of the blades decrease from root to tip so that weight of the blade decreases from root to tip to maintain a more uniform stress on account of centrifugal force.

The convex face 23 of each blade is preferably anticlastic or concave from root to tip, as shown particularly in Fig. 15, while the chordal face 24 is a helical surface generated by a straight line traveling in a helical path about an axis26 (Figs. 2 and 14) lying in the chordal face. As will appear later, the centers of gravity of the blade sections from root to tip lie in a line normal to the axis of rotation of the compressor. The axis 2-5 of the blade is parallel to this line.

The rotor and stationary blades are identical a lathe, while the root IQ of a rotor blade may be milled. It will be understood that the tenons 2| and root is may be formed before or after the finishing of the blade proper.

As shown particularly in Fig. 2, the rotor blades [4 projected on the root l9 lie entirely within the root.

Io shape the chordal face 24 of the blade, the blank is mounted in a suitable fixture on a milling machine which rotates the blank about the axis 26 as it moves under the cutter. As the blank moves past the milling cutter, it is rotated by the fixture about this axis through an angle A, Fig. 2, to provide the warped chordal face 24.

The convex surface 23 of the blade is formed by mounting one or more of the blade blanks on a lathe fixture 28, shown diagrammatically by dotted lines in Figs. 13 to 15, inclusive, with the flat or chordal face 24 of the blank disposed inwardly. The blank is secured to the fixture so that the axis 26 of the helix of the chordal face is inclined away from the axis of rotation of the fixture from the root to the tip of the blade, and inclined toward the leading edge of the blade from the root to the tip of the blade. The fixture is then placed in a. lathe and the convex surface is formed by turning a cylindrical surface on the blank so as to have the appearance illustrated in Figs. 13 and 14.

By inclining the axis 26 of the helix with respect to the axis of rotation of the lathe fixture, the chordal face of the blade is inclined toward the convex face, from the root to the tip, resulting in a decrease in the cross-sectional area and weight of the blade from the root to the tip.

It is desirable, although not necessary, to have the convex surface of the blade slightly concave in a longitudinal direction in order to keep the centers of gravity of the cross-sectional areas from root to tip substantially in a straight line normal to the axis of the compressor hub l3. This may be accomplished by means of a grinding wheel 3|, shown in Fig. 15, having a cutting face 32 shaped to grind the desired concavity. The wheel is rotated against the rotating fixture and blank producing the concavity 33 in the convex face of the blade.

The modified

blades

34 and 35 shown in Figs. 16 and 17, respectively, differ from the blade described above in that the convex faces are elements of cones rather than of a cylinder. The

blades

34 and 35 are made in exactly the same manner as the first blade except that in turning the convex face they are mounted on fixtures, shown schematically at 36 and 31, respectively. The fixtures are placed in a lathe and the convex surface formed by turning a conical surface on each of the blanks so that these blades have the appearance shown in Figs. 16 and 17.

The blade 34 is turned so that its convex surface is an element of a cone whose diameter decreases from the root to the tip of the blade. By forming the blade 34 in this manner, the chordal width of the blade tip is substantially less than the chordal width at the root of the blade, but the tip thickness may approximate the root thickness.

The convex surface of the modified blade 35 is an element of a cone whose diameter increases from the root to the tip of the blade. By forming the blade in this manner, the chordal width at the blade tip may approximate the chordal width at the root of the blade and the thickness of the blade at the tip is substantially less than at the root.

It is to be understood that in forming each of the

blades

34 and 35, all of the steps in making the blade shown in Figs. 13 to 15 are employed. The chordal face of these blades is helical but, as mentioned above, the convex surfaces are elements of cones rather than of a cylinder.

It is to be understood that one or more blanks may be mounted on the fixtures described above so that one or more blades may be formed in one operation.

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. In an axial-flow compressor or blower, blading wherein each blade is of circular segment section from the root to the tip, has a convex face whose root and tip radii are the same and has a chordal face inclined toward the convex face from the root to the tip.

2. A blade as recited in claim 1 whose convex face is of uniform radius from the root to the tip.

3. A blade as recited in claim 1 whose convex face has gradually decreasing radii from the root to an intermediate section and then gradually increasing radii from the latter to the tip.

4. In an axial-flow compressor or blower, blading wherein each blade has a convex face and a chordal face, said convex face being an element of a conical surface and said chordal face being generated by a straight line intersecting said conical surface and moving in a helical path from the root, to the tip of the blade 5. In an axial-flow compressor or blower as set forth in claim 4 wherein the conical surface is of increasing diameter from the root to the tip of the blade.

6. In an axial-flow compressor or blower as set forth in claim 4 wherein the conical surface is of decreasing diameter from the root to the tip of the blade.

7. In an axial-flow compressor or blower, blading wherein each blade is of substantially segment section from the root to tip, has a chordal face, and has a convex face which is an element of a surface of revolution generated by a curved line moving in a circular path about an axis disposed in the plane of the curved line, said curved line being concave with respect to said axis.

8. In an axial-flow compressor or blower, blading wherein each blade is of substantially segment section from the root to the tip, has a convex face which is an element of a surface of revolution generated by a curved line moving in a ment section from the root to the tip, has a convex face which is an element of a surface of revolution generated by a curved line moving in a circular path about an axis disposed in the plane of the curved line, said curved lin being concave with respect to said axis, and has a chordal face which is inclined toward the convex face from the root to the tip and which is generated by a straight line moving in a helical path from the root to the tip, the axis of said helical path being disposed at an angle to the first-mentioned axis.

10. In an axial-flow compressor or blovfr, blading wherein each blade includes a root for securing the same in the compressor and has a body portion of segment section from the root to the tip, the body portion has a convex face and a chordal face inclined toward the convex face from root to the tip, and whereinthe projection of said body portion lies entirely within said root.

ARNOLD H. REDDING.

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

UNITED STATES PATENTS Kohler Dec. 13, 1932