US3059834A

US3059834A - Turbo rotor

Info

Publication number: US3059834A
Application number: US716504A
Authority: US
Inventors: Hausammann Werner
Original assignee: Individual
Current assignee: Individual
Priority date: 1957-02-21
Filing date: 1958-02-20
Publication date: 1962-10-23
Anticipated expiration: 1979-10-23

Description

Oct. 23, 1962 w. HAUSAMMANN TURBO ROTOR 2 Sheets-Sheet 1 Filed Feb. 20, 1958 INVENTOR. Werner Hausa/" a 4 5 S. 329%- flflarn y Oct. 23, 1962 w. HAUSAMMANN' TURBO ROTOR 2 Sheets-Sheet 2 Filed Feb. 20, 1958 I N V EN TOR. Werner Haas 0mm 0n n Attorney 3,059,834 Patented Oct. 23, 1962 3,059,834 TURBO ROTOR Werner Hausammann, Dahliastrasse 16, Zurich, Switzerland Filed Feb. 20, 1958, Ser. No. 716,504 Claims priority, application Switzerland Feb. 21, 1957 Claims. (Cl. 230-434) The present invention relates to turbo rotors and more particularly to a rotor for an axial compressor in which the operating fluid moves at supersonic speeds.

In fluid operated apparatus it is desired to increase the energy of each particle of the fluid medium to the same extent. In the event that the peripheral speed of the rotor is substantially smaller in the hub region than at the ends of the blades or vanes, it is very difiicult to obtain this condition in spite of the unfavorable ratio between the diameter of the hub and the outer diameter of the rotor which is frequently present in axial compressors.

The energy given to the fluid medium depends not only on the circumferential speed but also on the amount of deflection of the flowing fluid. In order to produce suificient energy in the region of the rotor hub, it is necessary to deflect the flowing fluid at the inner ends of the rotor blades to a greater extent than at the outer ends of the rotor blades. The deflection is mainly obtained by the curved shape of the blade profiles, and according to the constructions of the prior art the curvature of the rotor blades or vanes corresponds to a circular shape of the mean camber line. In order to obtain a substantially constant energy increase in direction of the radius, it is necessary to reduce the curvature of the blades from the hub region toward the blade ends.

Due to the increase of the circumferential speed in radial direction, the angle between the chord of the blade profile and the circumferential direction will generally decrease in outward direction, resulting in a twisted shape of the blades.

Rotor blades constructed in this manner have blade portions which are inclined with respect to the radial direction so that the centrifugal force acting on the blades produces a bending moment on the blades which mainly acts on the root of the blade in the hub region. In the event that the circumferential speeds are very high, for example above 350 m./ sec. it is extremely difiicult to control the bending moment produced by the centrifugal force.

It is one object of the present invention to overcome this disadvantage of the prior art constructions, and to provide a rotor for a fluid operated machine, such as a supersonic compressor, in which no bending moments are produced by the centrifugal force during rotation.

Another object of the present invention is to provide a turbo rotor in which the blades extend in direction of an associated radial vector passing through the axis of rotation.

Another object of the present invention is to provide a turbo rotor whose blades have a mean camber surface which is a right helicoid.

With these objects in view, the present invention mainly consists in a turbo rotor which comprises a supporting body having an annular surface and an axis of rotation; and a plurality of circumferential'ly spaced blade means projecting from the annular surface of the supporting body. In accordance with the present invention, each blade means has in axial direction at least two parts having different mean camber surfaces, and at least the mean camber surface of one of the two parts is a right helicoid having the genera-trix thereof extending in direction of an associated radial vector passing through the axis of rotation of the rotor.

Preferably, the axis of the helicoid coincides with the axis of rotation.

The term right helicoid is used in the present application to describe a surface formed by a straight line generatrix gliding along a helix at a right angle to the axis of he helix. A right helicoid can also be described as a surface produced by turning movement and axial shifting of a straight generatrix about and along an axis which is intersected by the generatrix at a right angle. The ratio between turning angle and axial shifting distance is constant.

The mean camber line of a cross section of a blade is the locus of the centers of circles which are enveloped by the outer surfaces of the blades. Assuming an infinite number of adjacent cross sections between the inner and outer ends of a blade, the mean camber lines of such cross sections of the blade will together form an imaginary surface extending within the blade and being characteristic for the shape of the same. This imaginary surface is described as mean camber surface in the present application.

The peripheral surface of the hub which supports the rotor blades is either a surface of revolution which may include differently shaped surface portions, or a surface which is not a surface of revolution and includes a portion inclined to planes passing through the axis of the hub and to planes perpendicular to the axis of the hub.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings, in which:

FIG. 1 is a perspective view illustrating a rotor according to the present invention;

FIG. 2 is a fragmentary schematic developed view of the embodiments of FIG. 1;

FIGS. 3-6 are fragmentary schematic developed views corresponding to FIG. 2. and illustrating other embodiments of the present invention;

FIG. 7 is a fragmentary schematic cross sectional view of the rotor taken on line 77 in FIG. 10;

FIG. 8 is a fragmentary schematic sectional view taken in a plane perpendicular to the axis of rotation, and illustrating a modified construction which may be combined with all embodiments of the present invention;

FIG. 9 is a fragmentary side view illustrating a hub portion and a blade in accordance with the embodiment of FIGS. 1 and 2;

FIG. 9a is a fragmentary side view illustrating a modified hub portion;

FIG. 10 is a developed view similar to FIG. 2 and illustrating a further modified embodiment of the invention;

FIG. 11 is a fragmentary perspective view illustrating a rotor according to the present invention in which the hub surface is not a surface of revolution;

FIG. 12 is a fragmentary sectional view taken on line 12-12 in FIG. 1 1;

FIG. 13 is a fragmentary 13-13 in FIG. 12.; and

FIG. 14 is a fragmentary sectional view taken on line 14-14 in FIG. 12.

Referring now to the drawings, and more particularly to FIG. 1, a rotor according to the present invention includes a hub body 1 and a set of blade means 2. The outer surface of the hub can be constructed in different ways. The hub surface may be cylindrical, or conical, or be constructed as shown in FIGS. 1 and 9 in which the hub surface has a cylindrical surface portion 1a and a conical surface portion 1b, with the conical surface porsectional view taken on line tion increasing in diameter in direction of the flow of the fluid. The hub surface may also be modified as shown in FIG. 9a by merging the cylindrical and conical portion into a continuously and gradually curving surface.

The outer hub surface need not be a surface of revolution, but is advantageously constructed as shown in FIGS. 11-14. This hub construction is not an object of the present invention, and disclosed in my U.S. Patent 2,918,- 254, filed on May 10, 1955. However, this hub construction cooperates in a particularly advantageous and novel manner with the blade means of the present invention, and the combination of the specific hub construction with the specific blade construction shown in FIGS. 11-14 produces a particularly advantageous operation of the rotor.

The rotor shown in FIGS. 11-14 includes a shaft 105, a hub 101, and rotor blades 103. The outer hub surface 104 includes two cylindrical end portions 107 and 108, and an inclined bulge or shoulder 104a. At least one surface of the shoulder 104a is inclined at an acute angle with respect to planes passing through the axis of the rotor, and to planes perpendicular to the rotor axis. The hub surface 104 together with the

outer surfaces

103 and 103 of two adjacent rotor blades 103, form ducts 102 which are outwardly bounded by an annular surface, not shown in the drawings. FIG. 12 shows the outline 106 of the hub surface 104 in a section perpendicular to the axis. FIGS. 13 and 14 show, respectively, the outlines D and E in axial sections.

The hub constructions shown in FIGS. 1, 9 and 11 are advantageously combined with the various blade constructions of the present invention which will now be described.

Referring now to FIGS. 1 and 2, a plurality of blades or vanes 2 are shown, each of which includes an upstream part 24 located on the left of FIG. 2, and a downstream part 25 located on the right as viewed in FIG. 2. The upstream part 24 has a mean camber surface 4, and the downstream part 25 has a mean camber surface 5, which together form the mean camber surface 3 of the blade, and join along a line 6.

In accordance with a preferred embodiment of the present invention, the mean camber surface 4 is a right helicoid, and the mean camber surface 5 is a right helicoid having a pitch angle 6 greater than the pitch angle a of the helicoid 4. Each mean camber surface is defined by mean camber lines all points of which are on a radius.

However, it is also contemplated to construct a blade in which only one of the camber surfaces 4 and 5 is a right helicoid, and it is preferred to make the mean camber surface of the upstream portion 24 a right helicoid.

In the construction of FIG. 3, each blade includes three

integral parts

7a, 8a, 9a, having mean camber surfaces 7, 8 and 9, which are right helicoids of different pitch angle.

In the construction of FIG. 4, each blade means 10a has a mean camber surface 10 which is continuously curved, and includes the mean camber surface 11 of the upstream blade portion, and the mean camber surface 12 of the downstream blade portion which consists of several right helicoids having different and increasing pitch angles. Due to the gradual change of the pitch angle, the mean camber surface is a substantially continuous surface, and the outer lateral surfaces of the blades have a corresponding continuous shape.

In the embodiment of FIG. 6, which is similar to the embodiment of FIG. 3, each blade 10b includes three portions whose mean camber surfaces 7, 8 and 9 are right helicoids of different pitch angles increasing in down stream direction. The outer lateral surfaces of the blade 10b are continuous and gradually merge into each other, which is not the case in the embodiment of FIG. 3.

Blades whose mean camber surface consist of two mean camber surfaces which are right helicoids are particularly desirable from the point of view of simple manufacture. The outer surfaces of the two portions are substantially right helicoids, and can be formed by turning operations. The helicoid surfaces of the lateral surfaces of the blades have a pitch and generatrix corresponding to the desired variation of the blade thickness in flow direction, and in radial direction.

In the embodiment of FIG. 10, the different pitch angles of the mean camber surfaces 27 is so chosen, that it is possible to form one lateral outer surface 26 of the blade as a single right helicoid. The other lateral outer surface of the blade is formed by two right helicoids having different pitch angles.

FIGS. 1 and 9 show a hub 1 including a cylindrical portion 1a, and a conical portion 1b flaring in downstream direction. A blade is shown which has an upstream portion 24 and a downstream portion 25 corresponding to FIG. 2. The portion 25a of the downstream edge of portion 25 is inclined to the axis of rotation, and consequently does not coincide with the generatrix of the mean camber surface, while the inner portion of the downstream edge of portion 25 is perpendicular to the axis of rotation. While FIG. 9 shows the downstream edge of the blade to be inclined, it is also possible to incline the upstream edge of the upstream portion 24.

Such inclined edges reduce the axial extension of the blades in radial direction, which results in a more uniform energy increase in radial direction.

FIG. 2 illustrates a feature of the present invention, which is advantageously employed in all embodiments, but is shown in connection with the embodiment of FIGS. 1, 2 and 9. The blades are spaced in circumferential direction such a distance, and the locations of the mean camber surfaces 4 of the upstream portions 24 are so chosen that a line 22 from the upstream edge 21 of each blade 20 drawn perpendicular to the mean camber surface 4 of the usptream portion 24 of the adjacent blade, intersects the respective mean camber surface 4 at a point of intersection 23.

In the embodiment of FIG. 5 the upstream part 40 of each blade means is separated from the downstream portion 50. The mean camber surfaces 41 and 51 are right helicoids of different pitch angle. The outer surfaces of the two parts are preferably at least partly also right helicoids.

The mean camber surfaces of the various embodiments have been described to be right helicoids. As is shown in FIG. 7, the axis of the right helicoids preferably coincides with the axis of rotation 15 of the hub 1. Two generatrices 13 and 14 of two blades are indicated to pass through the axis of rotation 15. In this arrangement, the centrifugal forces acting on each blade will produce no bending moments on the

root portions

16 and 17 of the blades.

In the modified construction shown in FIG. 8, the generatrix 13a of each blade does not pass through the axis of rotation 15, but is parallel to an associated radial vector 13b passing through the axis 15. The radial vector 13b and the generatrix 13a are spaced a distance d. It will be understood that each blade has a generatrix which is parallel to a different associated radial vector.

Due to the fact that the mean camber lines are right helicoids, the centrifugal forces acting on the blades in the embodiment of FIG. 8a at the same angle along the entire axial length of each blade, and the amount of such centrifugal force can be exactly determined by suitably choosing the distance d. The moment produced by the centrifugal force on each blade is so chosen as to counteract the moment produced on each blade by the dynamic force 28 produced by the flowing fluid. When the bending moments produced by the centrifugal force and by the flowing fluid are balanced, no bending moment is produced on the blade means.

In FIG. 9 the upstream part 24 and the downstream part 25 of the blade are shown to join in the transverse plane in which the two hub surface portions: 1a and 1b join. This is, however, not necessary, and the hub surface may be constructed as desired with diiferent surface portions being joined axially spaced from the joining line of the upstream and downstream portions of the blades. This is, of course, particularly true with respect to the construction shown in FIGS. 11-14.

The apparatus of the present invention is particularly advantageously employed for a gaseous medium moving at supersonic speed through the rotor of the invention. Blade means of the type shown in FIGS. 2 and 3 in which the lateral outer surfaces of the upstream and downstream portions join along edges, for example the edges 6a in FIG. 2, have been found particularly advantageous when the relative speed of the gaseous medium at the moment of entering into the rotor is supersonic.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of rotors having vanes differing from the types described above.

While the invention has been illustrated and described as embodied in a turbo rotor having blades including an upstream and a downstream portion whose mean camber surfaces are right helicoids of different pitch angle having a common axis coinciding with the axis of rotation of the rotor, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be secured by Letters Patent is:

1. Turbo rotor comprising a supporting body having an annular surface and an axis of rotation; and a plurality of circumferentially spaced blade means fixed to and projecting radially from said annular surface of said supporting body, each blade means having at least an upstream part and a downstream part, and each said part of each blade means comprising an aerofoil section having in the direction of rotation leading and trailing faces extending substantially along right helicoid-s generated by generating lines extending perpendicular to said axis and moving helically along said axis, the pitch angles of at least said trailing faces being different, and each upstream part of each blade means if radially split midway between said faces defining at the split a mean camber surface generated by a line extending perpendicular to said axis and advancing helically along said axis in a downstream direction from said upstream end of each upstream part of each blade means.

2. Turbo rotor comprising a supporting body having an annular surface and an axis of rotation; and a plurality of cireumferentially spaced blade means fixed to and projecting radially from said annular surface of said supporting body, each blade means having at least an upstream part and a downstream part, and each part of each blade means comprising an aerofoil section having in the direction of rotation leading and trailing faces extending substantially along right helicoids generated by generating lines extending perpendicular to said axis and moving helically along said axis, said leading and trailing faces of said parts merging into each other, the pitch angles of at least said trailing faces being different, and each part of each blade means if radially split midway between said faces defining at the split a. mean camber surface generated by a line extending perpendicular to said axis and advancing helically along said axis in a downstream direction from said upstream end of each part of each blade means, said mean camber surfaces of said par-ts being right helicoids, having different pitch angles.

3. A rotor as set forth in claim 1 wherein said annular surface of said supporting body includes two different surfaces of revolution from which said upstream parts and downstream parts of said blade means respectively project.

4. A rotor as set forth in claim 1 wherein said upstream and downstream parts are separated, each part having upstream and downstream edges.

5. Turbo rotor comprising a supporting body having an annular surface and an axis of rotation; and a plurality of circumferentially spaced blade means fixed to and projecting radially from said annular surface of said supporting body, each blade means having at least an upstream part and a downstream part, and each part of each blade means comprising an aerofoil section having in the direction of rotation leading and trailing faces which intersect at the upstream end of each blade means, each part of each blade means if radially split midway between said faces defining at the split a mean camber surface being a right helicoid generated by a line extending perpendicular to said axis and advancing helically along said axis in a downstream direction from the upstream end of each part of each blade means, said mean camber surfaces of each part being right helicoid having different pitch angle, the axial extension of said upstream part and the circumferential spacing of said blade means being selected in such a manner that a line from said upstream edge of said upstream part of a blade means perpendicular to the mean camber surface of said upstream part of the adjacent blade means intersects said mean camber surface of said adjacent blade means, said downstream part having a downstream edge at least partly inclined to the respective radius and to said axis of rotation, said leading and trailing faces of said parts of said blade means extending along right helicoids, said leading faces and trailing faces of the upstream part and of the downstream part of each blade merging into each other, the pitch angles of at least the trailing faces of each blade means being different.

References Cited in the file of this patent UNITED STATES PATENTS 712,424 Tyzack Oct. 28, 1902 777,360 Wyand Dec. 13, 1904 979,735 Bennett Dec. 27, 1910 1,034,773 Favata Aug. 6, 1912 1,744,709 Moody Jan. 21, 1930 1,959,703 Birmann May 22, 1934 2,313,413 Weske Mar. 9, 1943 2,314,572 Chitz .Mar. 23, 1943 2,429,324 Meisser Oct. 21, 1943 2,469,125 Meisser May 3, 1949 2,645,086 Carter July 14, 1953 2,721,693 Fabri et al. Oct. 25, 1955 2,732,999 Stalker Jan. 31, 1956 2,735,612 Hausm'ann Feb. 21, 1956 2,830,753 Stalker Apr. 15, 1958 FOREIGN PATENTS 1,566 Australia Apr. 24, 1926 332,859 Great Britain July 31, 1930