US2797858A

US2797858A - Radial compressors or turbines

Info

Publication number: US2797858A
Application number: US417847A
Authority: US
Inventors: Nuell Werner T Von Der
Original assignee: Garrett Corp
Current assignee: Garrett Corp
Priority date: 1954-03-22
Filing date: 1954-03-22
Publication date: 1957-07-02
Anticipated expiration: 1974-07-02
Also published as: FR1121235A; GB765908A

Description

July 2, 1957 w. T. VON DER NUELL 2,797,858

RADIAL COMPRESSORS OR TURBINES Filed March 22, 1954 F/'g./.

2o W I 24 .8 ///1 I I4 I5 ERNER I V0 BY $4 #7 M l l l l United States see RADIAL COMPRESORS OR TURBINES Werner '1. von der Nuell, Santa Monica, Calif., assignor to The Garrett Corporation, Los Angeles, Calif, a corporation of California Application March 22, 1954, Serial No. 417 ,847

Claims. (Cl. 230-114) The present invention relates to radial compressors or turbines, and more particularly to means for effecting efficient energy distribution over the surface of the rotor blades of such machinery and adapted for use as a diffuser arrangement for a radial compressor, or as a nozzle structure for a radial turbine when operating with compressible fluids moving at high Mach numbers.

The radial clearance between the blades of a wheel and vanes adjacent the periphery thereof influences the performance characteristics of the wheel whether it be used as a turbine, compressor, or fluid pump. During operation of a conventional variable area nozzle adjacent a bladed wheel, radial clearance of the vanes relative to the wheel blades increases or decreases according to angular adjustment thereof. Such progressive increase in vane, or nozzle clearance adjacent the periphery of a bladed Wheel may reduce the efliciency thereof when operating at an angular position different from the originally designed position, and therefore it limits the practical range within which nozzles or vanes may be angularly adjusted.

According to the present invention, and in order to accomplish substantially equal energy distribution on the surfaces of wheel blades, the blade extremities are disposed at an angle to the axis of the wheel, whereby they describe a frusto-conical path when the wheel rotates. A plurality of nozzles are arranged in conforming angular relation to the wheel blade extremities. The pivotal axis of each nozzle or vane intersects the angularly disposed edges thereof at or near a median point thereon, whereby pivotal movement of each vane about its axis causes a portion of said angularly disposed edge to move toward the conforming edges of the wheel blades while another portion of said angularly disposed edge moves away therefrom. in this manner a substantially constant mean clearance may be maintained between co-operating edges of nozzles or vanes and wheel blades throughout a considerable range of adjustment or load changing variation thereof whereby substantially equal fluid energy distribution on the wheel blades is maintained during pivotal adjustment of the vanes.

An object of the invention is to provide means for effecting efi'lcient fluid energy distribution over surfaces of compressor or turbine wheel blades when operating with compressible fluids moving at high Mach numbers.

Another object of the invention is to provide vane means which, when operated throughout a wide range of area adjustment, will maintain a substantialy constant mean clearance with respect to peripheral portions of a bladed wheel.

A further object of the invention is to provide means which may be employed in either turbines or compressors for maintaining 'efliciency thereof throughout a considerable range of flow variation.

Another object of the invention is to provide means which permits reduction of the disc shroud diameter of a bladed wheel, thereby reducing the centrifugal stress level therein in operation.

A further object of the invention is to provide means for maintaining substantially constant mean clearance of variable vanes with a bladed wheel which is simple and economical to produce in proportion to its function and yet very efficient and durable in operation.

Other objects and advantages of the invention may be apparent from the following specification, claims, and drawing of this application, in which:

Fig. 1 is a fragmentary axial sectional view of a bladed wheel and variable vane structure according to the present invention; and

Fig. 2 is a fragmentary perspective view of a bladed wheel having a plurality of co-operating vanes constructed according to the present invention.

A wheel 10 is substantially conventional in construction and is generally of the radial type, being useful either in a centrifugal compressor or a centripetal turbine. This wheel is provided with blades 11 having radially extending portions terminating in outer edge portions 12 which are disposed at an angle to the axis 13 of the wheel 10. The edges 12 of the blades 11 converge toward the axis 13 of the wheel. Thence, the blades at said edges 12 form the periphery of the wheel which when rotating describes a frusto-conical surface of revolution adjacent to which vanes 14 are positioned. The angle of the edges 12, with respect to the axis of the wheel, provides for substantially equal flow path lengths, through the wheel, adjacent wheel shroud 24 and stationary or casing shroud 25. This arrangement provides for more even loading of the overall area of the blades and thereby renders the wheel more efficient when operating, to either extract energy from, or add energy to, a compressible fluid.

The vanes 14 are provided with edges 15 substantially parallel to and conforming angularly with the edges 12 of the turbine wheel blades 11. The vanes 14 at their

edges

16 and 17 are confined by

passage walls

18 and 19. Each vane 14 is provided with a trunnion 20 axially parallel with the wheel axis 13. The axis 21 of each vane 14 intersects the

edges

12 and 15 of the wheel blades 11 and vanes 14 respectively near the median point 22 lying between the limits of

said edges

12 and 15. Under ideal conditions the median point 22 should be half way between the extremities of these edges but, due to certain mechanical considerations, may vary so that the median point 22 may not be half way between the limits of the co-operating wheel blade and vane edges. When the wheel 10 is constructed as shown in Fig. 1 wherein the wheel blade and vane edges are directed at the angle as shown, the periphery 23 of the shroud disc portion 24 of the wheel 10 may be relatively small in proportion to the overall periphery of the wheel at the outer extremities of the blades thereof. Such diametrical proportions permit the back disc 24 of the wheel 10 to be operated with relatively light centrifugal loading in proportion to the speed-diameter ratio of the wheel.

The operation of the wheel and vane structure of the present invention is substantially as follows.

Whether the wheel 10 is rotating and being operated as a pumping wheel or whether 'it is driven as a turbine by gas directed through the vanes 14, the adjustable operation of the vanes with respect to the peripheral edges of the wheel blades is substantially the same. In order to vary blade loading or diffusion of fluid therefrom the vanes 14 may be pivoted about their axes 21 whereby their edge portions 15 extending inwardly of each axis 21 will be caused to move away from the edges 12 of the wheel blades, while the portions of the edges 15 outwardly of the axis 21 will be caused to move toward the edges 12 of the wheel blades. In this manner a substantially constant mean clearance of the vane and co-operating blade edges may be maintained throughout a considerable range of angular adjustment of the vanes relative to the wheel.

The degree of angularity of the vane edges 15 with respect to the axis 13 of the wheel may be varied in proportion to the desired pivotal angle of the vanes 14 about the axes 21 thereof. Furthermore, such a degree of angularity may be varied for other design considerations as may be necessary. With this arrangement substantially equal clearance exists between the vanes and the wheel blades near both

shrouds

24 and 25. Since fluid flow path lengths through the wheel between the blades and along the

shrouds

24 and 25 may be made more nearly equal, a co-operative relationship exists between vane-to-blade clearance and fluid energy distribution on the blades. It will be understood that blade loading varies with the varying wheel radii along the

shrouds

24 and 25 and hence only approximate equalization of energy distribution throughout the surfaces of the blades will usually be accomplished. This substantial uniformity of energy distribution is adequate and of great benetion when rotating, a plurality of adjustable vanes having edges spaced from and substantially parallel to said outer edges of said blades, and means supporting said vanes for pivotal movement about axes which intersect said frusto-conical surface of revolution at a median location with respect to the limits of the outer edges of said blades.

2. An energy distributing mechanism arranged to maintain substantially constant mean clearance between variable vanes and the peripheral portions of a bladed wheel, I comprising: a bladed wheel having blades extending between the axis and the periphery thereof, said blades having outer edges which are angularly disposed to the axis of said wheel whereby said edges describe a general frusto-conical surface of revolution when rotating, a plurality of variable vanes having edges spaced from and substantially parallel to said outer edges of said blades,

and means supporting said vanes for pivotal movement about axes which intersect said frusto-conical surface of J revolution at a location between the limits of the outer edges of said blades.

3. In a mechanism for effecting eflicient fluid energy distribution over surfaces of a bladed wheel, said bladed wheel having blades extending between the axis and the periphery thereof, said blades having outer edges which are angularly disposed to the axis of said wheel whereby they describe a generally frusto-conical surface of revolution when rotating, a plurality of variable vanes having 1 edges substantially conforming to the outer edges of said blades, and means supporting said vanes for pivotal movement about axes which intersect said frusto-conical surface of revolution at a location between the limits of the outer edges of said blades.

4. In a mechanism for effecting efiicient fluid energy 7 distribution over surfaces of a bladed wheel, said bladed wheel having blades extending between the axis and the periphery thereof, said blades having outer edges which I are angularly disposed to the axis of said wheel whereby they describe a generally frusto-conical surface of revolution when rotating, a plurality of variable vanes having edges substantially conforming to the outer edges of said blades, and means supporting said vanes for pivotal movement about axes which intersect said frusto-conical surface of revolution at a location between the limits of 4 the outer edges of said blades, and a shroud on said wheel to which said blades are fixed, said shroud being of lesser diameter than the major diameter of said frusto-conical surface of revolution.

5. Mechanism for effecting efficient fluid energy distribution over surfaces of a bladed wheel, said bladed wheel having blades extending between the axis and the periphery thereof, said blades having outer edges which are angularly disposed to the axis of said wheel whereby they describe a generally frusto-conical surface of revolution when rotating, a plurality of variable vanes having edges substantially conforming to the outer edges of said blades, means supporting said vanes for pivotal movement about axes which intersect said frusto-conical surface of revolution at a location between the limits of the outer edges of said blades, the pivotal axes of said vanes being substantially parallel to the axis of said wheel.

6. In a mechanism for effecting efficient fluid energy distribution over surfaces of a bladed wheel, a wheel provided with blades including substantially radially disposed portions having outer edges forming the periphery of the wheel, the outer edges of said blades being disposed in generally converging relationship with the axis of said wheel, variable vanes having inner edges conforming with the outer edges of said blades, and means supporting said variable vanes for pivotal movement about axes intersecting said inner and outer edges at a location between the limits thereof.

7. In a mechanism for effecting eflicient fluid energy distribution over surfaces of a bladed wheel, a wheel provided with blades including substantially radially disposed portions having outer edges forming the periphery of the wheel, the outer edges of said blades being disposed in converging relationship with the axis of said wheel, variable vanes having inner edges conforming with the outer edges of said blades, means supporting said variable vanes for pivotal movement about axes intersecting said inner and outer edges at a location between the limits thereof, and a shroud on said wheel to which said blades are fixed, said shroud being of lesser diameter than the periphery of said wheel at the outer edges of said blades.

8. In a mechanism for effecting eflicient fluid energy distribution over surfaces of a bladed wheel, a wheel provided with blades including substantially radially disposed portions having outer edges forming the periphery of the wheel, the outer edges of said blades being disposed in converging relationship with the axis of said wheel, variable vanes having inner edges conforming with the outer edges of said blades, means supporting said variable vanes for pivotal movement about axes intersecting said inner and outer edges at a location between the limits thereof, and a shroud on said wheel to which said blades are fixed, said shroud being of lesser diameter than the periphery of said wheel at the outer edges of said blades, the pivotal axes of said vanes being substantially parallel to the axis of said wheel.

: supported in said chamber for rotation about the axis thereof, said wheel having blades extending between the central region and the periphery thereof, the outer ends of said blades terminating in edges disposed at an angle to the axis of said wheel; a plurality of diffuser vanes disposed in said passage, said vanes having edges substantially parallel to and spaced from the edges of said blades; and means pivotally supporting said vanes for adjustment about axes intersecting the angularly disposed edges of said blades.

10. In an elastic fluid mechanism, a casing forming a wheel chamber having passages communicating axially and peripherally therewith, the latter passage being substantially normal to the axis of said wheel chamber; a wheel supported in said chamber for rotation about the axis thereof, said wheel having blades forming passages communicating at opposite ends with the axial and peripheral passages in said casing, said blades terminating at the periphery of said wheel in planes disposed in angular relationship with the axis of said wheel; a plurality of diffuser vanes disposed in the passage at the periphery of said chamber, said vanes having edges parallel to and spaced from the angular edges of said blades; and pivot means extending substantially parallel to the axis of said Wheel, said pivot means supporting said vanes for adjustment about axes extending through the angular edges of said blades.

References Cited in the file of this patent UNITED STATES PATENTS