US3639075A

US3639075A - Turbomachinery vane adjustment mechanism

Info

Publication number: US3639075A
Application number: US884559A
Authority: US
Inventors: John R Erwin; Nicholas G Vitale
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1969-12-12
Filing date: 1969-12-12
Publication date: 1972-02-01
Anticipated expiration: 1989-02-01

Abstract

A radial flow compressor is shown with unique adjusting means for the diffuser vanes. The leading end portion of each blade is pivoted on the casing. Pintles project from the blades into eccentrics which are journaled in shafts mounted on the casing. The shafts are rotated, to get a highly accurate angular position of the vanes through the offset relation of the axes of the shafts, the eccentrics and the pintles.

Description

United States Patent Erwin et all.

[541 TURBOMACHINERY VANE ADJUSTMENT MECHANISM [72] Inventors: John R. Erwin, Paradise Valley, Ariz.;

Nicholas G. Vitale, Arlington, Mass.

[73] Assignee: General Electric Company [22] Filed: Dec. 12, 1969 [21] Appl. No.: 884,559

[52] 11.8. CI AIS/163, 415/149 [51 1 Int. (.1 r. ..F04d 27/00, F04d 15/00 158] Field of Search ..4l5/148166 [56] References Cited UNITED STATES PATENTS 2,189,252 2/1940 Reggio ..415/l63 2,645,410 7/1953 Bauger et al ..4l5/l63 2,770,943 11/1956 Beale 415/163 2,985,427 5/1961 Houghton 415/148 1 Feb. 1, 1972 2,994,509 8/1961 Walker ..4 1 5/150 2,976,013 3/1961 Hunter ..415/163 3,378,229 4/1968 Erwin ..415/l48 FOREIGN PATENTS OR APPLICATIONS 560,329 7/1958 Canada .415/163 Primary Examiner-Henry F, Raduazo Att0rney-Derek P. Lawrence, E. S. Lee, 111, Lee H. Sachs, Frank L. Neuhauser, Oscar B. Waddell and Joseph B. Forman 1 1 ABSTRACT A radial flow compressor is shown with unique adjusting means for the diffuser vanes. The leading end portion of each blade is pivoted on the casing. Pintles project from the blades into eccentrics which are journaled in shafts mounted on the casing. The shafts are rotated, to get a highly accurate angular position of the vanes through the offset relation of the axes of the shafts, the eccentrics and the pintles,

4 Claims, 5 Drawing Figures TURBOMACI-IINERY VANE ADJUSTMENT MECHANISM The present invention relates to turbomachinery in the nature of compressors and turbines and, more particularly, to an improved, adjustable guide vane system therefor.

Operation of turbomachinery at other than its design point can result in losses in efficiency which are quite disadvantageous. In other words, compressors and turbines are designed, aerodynamically, for optimum efficiency at a specified gas flow velocity, gas temperature, rotational speed and other parameters. When these parametric values of the design point are varied, there can be serious losses in efficiency.

One known approach to minimizing losses during off-design operation is to vary the angle of guide vanes which guide air to or from the rotor blades of the compressor or turbine. By changing the angles of such blades relative to the flow path, it is possible to optimize the orientation of the vanes to the direction of gas flow as well as to vary the effective area of the gas flow path.

In some cases extreme accuracy is required in adjusting vane angle during off design point operation. Such accuracy with the required mechanical stability has not been adequately provided by prior vane adjusting mechanisms for this purpose and, accordingly, one object of the present invention is to fulfill this need.

Further, radial flow turbomachinery requires minimum displacement of the edges of the vanes relative to the rotor and the invention accordingly has this further objective.

The above and other related objects and features of the invention will be apparent from a reading of the following description of the disclosure found in the accompanying drawings and the novelty thereof pointed out in the appended claims.

In the drawings:

FIG. 1 is a longitudinal section through a radial flow compressor embodying the present invention;

FIG. 2 is a section, taken generally on line lIII in FIG. 1;

FIG. 3 is a section similar to FIG. 1 showing vanes adjusted to a different position;

FIG. 4 is a side view of the vane-adjusting mechanism; and

FIG. 5 is an enlarged view ofa portion of FIG. 2.

Referring first to FIGS. 1 and 2, the illustrated compressor comprises a rotor disc rotatable around a central axis ofa shaft 11 which carries the disc. A second disc 12 is axially spaced from rotor disc 10 and also spaced radially from shaft 11 to define, with the rotor disc 10, an unobstructed curved inlet air passage 13 between the discs to direct air radially outward between the discs. In order to provide the proper swirl to the incoming radial air, inlet guide vanes may be provided at a distance from the center of rotation and radially upstream of the'rotor blades, as shown, to insure that they receive only radially flowing air, thus insuring two-dimensional flow through the passage between'the discs and eliminating the undesirable secondary vorticity and consequent losses. Inlet guide vanes 14 are preferably given a curvature for turning the incoming radial air in a direction opposed to the rotor or disc rotation to give the air a counterswirl or tangential velocity as seen in FIG. 2. This permits a high relative velocity to the rotor and the resultant total pressure relative to the rotor also is increased. Thus, a higher pressure ratio is obtained. For higher efficiency, lower pressure ratio, the guide vanes can direct the air in the direction of rotation. While the guide vanes may in some instances be eliminated, it is useful to have the guide vanes for efficient off-design operation which is further assisted by making them adjustable by pivoting about axis 15 in any suitable manner, not shown.

The air through the compressor is compressed by means of a single stage of compressor blades 16 which are highly cambered as shown in FIGS. 2 and 3 and are secured to the

discs

10 and 12 so that the discs and blades rotate as a unit. It is to be noted that the blades 16 are particularly located at a radial distance from the center of rotation so that they receive substantially radial flowing air only so the flow is two-dimensional, thus reducing the losses.

The compressor described is next provided with a rotating diffuser in combination with the two-dimensional flow by extending

discs

10 and 12 radially beyond the periphery of blades 16 to form a rotating vaneless diffuser passage 17. As in any diffusing flow passage, boundary llayer fluid becomes a problem, and the present invention has a built-in boundary layer control by providing diffuser passage 17 with rotating walls. It can be seen that by rotation of diffuser passage 17, the rotating sidewalls of the

discs

10 and 12 energize the boundary layer due to the centrifugal field on the particle, since all particles will have a tangential velocity equal to or greater than the rotational velocity of the rotor discs. The vaneless rotating dif' fuser passage 17 which diffuses the flow from a Mach. number of about 2.5 down to about 1.6 is followed by a stationary diffuser comprising vanes 18 closely spaced, radially from the diffuser passage 17 for further diffusion and resulting pressure rise of the air from the rotor. Any suitable collecting means such as scroll 19 connected to the stationary vaned diffuser may be employed to carry the pressurized air to a point of use.

With the construction just described, sealing problems are also minimized. The whole rotating structure is surrounded by closely spaced casing 21, and sealing means 23 are provided at a small radius on each disc between the disc and casing well inwardly of the disc outer periphery. This puts the seal at a lower rotational speed of the rotor compared to that of the rotor periphery. Because of the rotation of the air in the spaces between 12 and 21 and between 10 and 21, the pressure increases outwardly, and the pressure gradient across the seal 23 is lessened. With this construction no sealing is required at the periphery of the disc between rotating diffuser passage 17 and the stationary, vaned diffuser because the small sealed volume between casing 21 and the discs, once charged with air, is an effective seal itself for the air flowing through the compressor.

The preceding is a summary of the radial flow compressor described and claimed in US. Pat. No. 3,460,748, which is of common assignment with the present application.

The angular positions of the vanes 18 are adjusted by the mechanism now to be described. Each vane 18 has a pair of pintles 20, adjacent its leading edge, which project from its opposite sides. These pintles are pivotally received by holes formed in the radial side walls of the stationary diffuser, as provided by the casing. A second pair of pintles 22 also projects from the opposite sides of each blade 18, being spaced from the pintles 20. The pintles 22 are pivotally mounted on eccentrics 24 in holes which are offset from the axis of these eccentrics. The eccentrics 24, in turn, are pivotally mounted in holes which are formed in shafts 26. The shafts 26 are journaled in the casing 21 and have pinions 28 formed in their outer ends.

Ring gears 30 mesh respectively with each set of pinions 28 on opposite sides of the casing 21. The ring gears are held in place by annular retainers 32 which are secured to the casing 21 by screws 34. The ring gears are rotated by an actuator 36 which is pivotally mounted at one end in fixed relation to the casing 21. The rod 38, of the actuator, is secured to a trunnion block 40 which is mounted on a bracket 42. The legs of bracket 42 are attached respectively to the ring gears 30.

The actuator 36 is connected to an appropriate pressurized fluid source with suitable controls for displacing the piston rod as desired. The ring gears may thus be rotated to vary the angular setting of the vanes 18. FIG. 2 illustrates one setting, while FIG. 3 illustrates another setting. The described mechanism enables highly accurate control of the angular position of the vanes due to the fact that several degrees of ring movement are required for only a few degrees of vane movement. A device capable of measuring angular rotation may be attached to one of the shafts 26 to provide an accurate indication of vane angular position. By having the pintles 20 adjacent the leading edge of the blade, there is a minimal radial displacement of that edge when the blades are pivoted. This is significant in maintaining a minimum distance between the rotary diffuser discharge and the blades 18. This enables the leading edges of the vanes 18 to be maintained at the entrance to the stationary diffuser and is thus particularly effective in minimizing losses when supersonic flow exists.

It will further be apparent that the described system not only provides rugged support for the blades, but further enables the sidewalls of the diffuser to be smooth so that no turbulence is introduced by the angle-adjusting means.

The inlet guide vanes 14 could also be adjusted by a mechanism embodying the concepts described in connection with the vanes 18. However, the present invention is not necessarily required in vane-adjusting mechanisms where normal accuracy and normal displacement of the blade edgescan be tolerated.

While the present invention has unique applicability to the described type of compressor, its broader aspects are applicable to turbomachinery in general.

Having thus described the invention, what is claimed as novel and desired to be secured by Letters Patent of the United States is:

l. Turbomachinery having,

a row of vanes for guiding gas flow, said vanes being of an airfoil cross section from their leading to their trailing edges,

a casing having spaced, opposed walls defining a radial gas flow path through said vanes,

means for pivotally mounting each vane on said opposed walls about an axis adjacent one edge of the blade, means for oscillating said vanes about said pivotal mountings including for each vane,

a pair of aligned shafts journaled in said casing walls,

eccentrics journaled on said shafts, said eccentrics having a common axis offset from the shaft axis, and

means pivotally connecting the vane to the eccentrics about an axis offset from the eccentrics axis,

all of said axes being parallel,

said shafts having pinions on their outer ends,

ring gears respectively meshing with said pinions and means for simultaneously rotating the ring gears to vary the vane angle.

2. Turbomachinery as in claim 1 wherein,

the inner end surfaces of said shafts are flush with the surfaces of the respective walls and the eccentrics are mounted in bores formed in said shafts with their end surfaces flush with the end surfaces of the shafts.

3. Turbomachinery as in claim 2 further comprising,

a rotor having wall surfaces generally aligned with the wall surfaces of the casing, said rotor being closely spaced from said walls,

the means for pivotally mounting the vanes on the casing walls comprise pintles received by openings in said casing walls, said pintles being closely spaced from the edges, of the respective vanes, which are nearest the rotor, and

the means for pivotally mounting the vanes on the eccentrics comprise pintles extending into holes in said eccentrics 4. Turbomachinery as in claim 3 wherein,

the shafts have pinions formed on their outer ends and the rotating means includes a pair of yoked ring gears respectively meshing with the pinions of the first and second wall shafts and means for rotating the ring gears to vary the vane angle.

Claims

1. Turbomachinery having, a row of vanes for guiding gas flow, said vanes being of an airfoil cross section from their leading to their trailing edges, a casing having spaced, opposed walls defining a radial gas flow path through said vanes, means for pivotally mounting each vane on said opposed walls about an axis adjacent one edge of the blade, means for oscillating said vanes about said pivotal mountings including for each vane, a pair of aligned shafts journaled in said casing walls, eccentrics journaled on said shafts, said eccentrics having a common axis offset from the shaft axis, and means pivotally connecting the vane to the eccentrics about an axis offset from the eccentrics'' axis, all of said axes being parallel, said shafts having pinions on their outer ends, ring gears respectively meshing with said pinions and means for simultaneously rotating the ring gears to vary the vane angle.

2. Turbomachinery as in claim 1 wherein, the inner end surfaces of said shafts are flush with the surfaces of the respective walls and the eccentrics are mounted in bores formed in said shafts with their end surfaces flush with the end surfaces of thE shafts.

3. Turbomachinery as in claim 2 further comprising, a rotor having wall surfaces generally aligned with the wall surfaces of the casing, said rotor being closely spaced from said walls, the means for pivotally mounting the vanes on the casing walls comprise pintles received by openings in said casing walls, said pintles being closely spaced from the edges, of the respective vanes, which are nearest the rotor, and the means for pivotally mounting the vanes on the eccentrics comprise pintles extending into holes in said eccentrics

4. Turbomachinery as in claim 3 wherein, the shafts have pinions formed on their outer ends and the rotating means includes a pair of yoked ring gears respectively meshing with the pinions of the first and second wall shafts and means for rotating the ring gears to vary the vane angle.