US1744709A - Vane formation for rotary elements - Google Patents

Description

13.11.21,"!930'. L. F. MUDDY VANS FORMATION FOR ROTARY ELEMENTS Filed Jan. 29 1921 Z Sheets-Sheet 1 ah vahboz Jan. 21, 1930. L. F. MOODY 1,744,709

VANE FORMATION FOR ROTARY ELEMENTS Filed Jan. 29, 1921 2 Shuts-Sheet 2 Patented Jan. 21, 1930 UNITED STATES LEWIS FERRY, MOODY, OF PHILADELPHIA, IENNSYLVANIA FORMATION FOR ROTARY ELEMENTS Application filed January 29, 1921. Serial No. 440,889.

This invention relates to rotary impellers or runners for turbines,.pumps, blowers and the like and particularly to the blacling of such rotary elements. Hitherto'it has been -5 the practice to form the blades of a rotary propeller or runner as a succession of similar 1y formed and equally spaced vanes so that all the channels between the vanes are exactly alike. In many cases this leads to complitions of flow in the channels between the vanes so that the water tends to part from the surfaces or in other'ways to form wasteful eddies and cross currents in the passing fluid, par- F ticularly under conditions of operation different from the normal or designed conditions.

The object of this invention is to provide an impeller or runner overcoming these objections and in which wasteful disturbances in the channels between the blades will be avoided.

In the accompanying drawings illustrating the invention,

Figs. 1 to 4 are diagrammatic developments of turbine runners.

Fig. 5 is a vertical elevation of the turbine runner shown in Fig. 4,

Figs. 6 to 8 are diagrams of modifications, Fig. 9 is a vertical sectional view of a turbine having a runner in its conduit,

Fig. 10 is a diagrammatic development of a rotor for a pump,

Fig. 10 is a diagrammatic view of a pump, embodying my invention, and

Fig. 11 is a vertical elevational View of a. propeller.

In Fig. 1 a runner 7' of a hydraulic turbine is represented in diagrammatic development, the'rotationor movement of the runner being fromlefttoright and the vane structure shown being continued around the runner. Fluid flows to the runner through a radial passage 35, Figs. 5 and 9, surrounding the runner axis, a transition'space 36 and axial passage 37 and discharges from the runner into a draft tube cated forms of vanes and to uncertain condi-.

38 which enlarges in the direction of flow so as to produce deceleration of the discharged fluid. These passages a'redefined by walls formed as surfaces of revolution. Fixed guide vanes 39 and the usual movable .wicket gates 40 are also associated with the flow pas: sages, the wicket gates imparting a whirl to the flow entering the transition space. The vanes are in the form of a series of groups, each group comprising a lower vane 42 and an upper vane e. In another aspect the vanes may be considered as comprising an upper serles o and a lower series a, the series being offset with relation to eachother. Varies 0 may be considered to take the place of an upward extension of the vanes 'v, as indicated by the dotted line continuation of these vanes 22 in Fig. 1. By this subdivided or grouped vane structure the guiding surfaces of the vanes may be positioned more advantageously with relation to each other than if they were contained in a single vane, for instance as illustrated in Fig. 2' there is often a tendency of the flow, particularly along the rear surfaces 'of the vanes, to develop wasteful eddies-and disturbances. In the runner or impeller of a turbine or pump and also in the case of propellers and compressors the interactionof the fluid and vanes produces a region of increased pressure adjacent to the face or driving side a of each blade and a reglon of reduced pressure or partial vacuum adjacent to the back 0 of each vane. The flow at and near the face a (Figs. 2 and 3) is under conditions similar to those existing in a contracting nozzle and in this region. the tendency toward eddy formation is reduced. At

and near the back a of a blade, however, there is a tendency ofthe flow to lower in pressure and form eddies-and leave the back surface of the vane, and particularly under part load the conditions of flow can be considerably improved by roviding the vane above the vane 41 as s own in Fig. 1,,tend1ng to guide the -flow against the back of the preceding 9 vane. This smaller vane 0 may be given any desired form and inclination, for instance it may be given greater inclination than that of the vane o and increased curvature in order to deflect the Water through a greater angle. This auxiliary vane a will have the effect of receiving the flow and deflecting it toward the back of the vane c in such a way as to prevent the formation of an eddy at this point. The result of the use of the grouped vanes will be to enable the runner to handle the flow with better efficiency through a wide range of angles of the relative entrance velocity so that in the runner of this invention improved part gate efliciencies and better performance under varying head will be attained. This grouping will also avoid the occurrence of unstable conditions in the runner such as' sometimes occur in runners of very high spethe increased pressure at a on the vane face of fiow produced by the vane face and deceler ation by the back. Most high-speed turbines are therefore suction turbines inthe portion of the buckets toward the backs of the vanes, and turbines with positive reaction in the portion of the buckets toward the vane faces. The inequality in velocityat d and b may be reduced by increasing the number of 1 K vanes but this increases the surface'friction.

/It then becomes a problem to design the runner for eflicient guiding and diffusion of the flow at the backs of the vanes, the action at this oint partaking of the nature of the flow in a raft tube and'the efliciency of the turbine suffering when the diffusion isltoo rapid and.

I. the water tends to leave the backs of the vanes and eddies are formed. In the modification illustrated in Fig. 3 the diffusion areaaat the back of the vanes v are broken up into a num-.

ber of smaller diffusion channels by the auxilia vanes o 1),, one or more for each vane v. e surfaces of this group of vanes o e, are arranged with relation to each other so.

thatthe difiusion between them is gradual at all points and not so ra id as to cause the flow to de art from the guldes and set up wasteful disturbances. Thus in this figurea diffusing passage is formed between the back of tion of flow thus causing acceleration of the I flow. ,Hence broadly there are successive accelerating and decelerating passages, one following the other.-

Anothenmethod of grouping the vanes with relation to each other is illustrated in Figs, 4 to 6 wherein each group. of similar vanes is inclined with respect to its direction of rotation. This permits an advantageous respacing after the most favorable shape and arrangement of the individual vanes have been determined. In acting upon the face of a. vane," the deflecting of the water sets up pressure, and on the back of the vane the pressure is reduced; the difference between the two pressures causes the usefuldriving force on the 'vanes. The frictional resistance of the vanes causes a backward drag on the vanes which reduces theeflective driving force. An efiicientform of vane is one which will exert a large force in the direction of motion, but a small resistance in .the direction of flow. In an efiicient vane the angle of the resultant force with the direction of motion high frictional resistance areinvolved.

When the rotational speed of the runner is high, a. small angle of inclination of the vanes to the tangential direction may be used, and a small number of vanes can be adopted and given a favorable arrangement. If the usual vanes are spaced too closely the water instead of having a'tendency to leave the back'of the vane and to reduce the pressure allover the back surface, as in Fig. 1 is directed back on the surface and the area of reduced pressure is brought down to only a small space near the entrance edge of the vane. If on the other hand the vane spacing is increased beyond a point where there ceases to be any further pressure'reduction in the back of the vanes,

there will, of course, be a loss due to the water passing between the vanes without having any effect upon them..

Sup sethere has been found by'experiment t e most favorable arrangement of the t to eachothenas in Figure vanes with res 1, and that it is. desired to design a. runner in which the inclination of the vanes to the direction of motion of the runner is greater, in.

changed by merely revolving them and keeping them in the same locations, their relation to each other will immediately be altered, and the favorable pressure conditions will be lost.

If however a group of vanes v 0 b for example as in Fig. 4, is inclined as a whole to a radial plane, keeping the same relative positions of the vanes, these can then be followed by a separate group spaced far enough away to avoid disturbing the pressure conditions in the back of the Vane immediately preceding the next group. In this manner a runner will be producedhaving vanes arranged in groups of say two or three to each group, as shown in, Figures 4, v6 and 7 The resulting arrangement may be viewed as if each vane in an ordinary runner were subdivided into two or three smaller vanes with intermediate passages between them. It thus becomes possible to avoidthe effect of too close or too wide spacing." Instead of the lower half of the vane being inefficient, due to the preceding vane directing water back against it, by openingthe intermediate p assage the lower half of the vane can be made as efl'ective'as the first halfwithdut exposing any greater extent of'surface to the water than" in the first case. In these figures, as in Fig. 3, there are decelerating and accelerating passages, one followed by the other. For instance the passage between vanes c and '12 enlarges in the d rection of flo w or permits deceleration while the passages between ,vanes o and b or vanes and o contract in the direction of flow and thus cause acceleration. Asshown in Fig. 6 the center line of the group of vanes may be inclined downward to the right instead of to the left as shown in Fig. 4, and as illustrated in Fig.

7 the grouping may be provided .by simply subdividing a single vane into two sub-vanes e and '0, with a channel 20 between them.

The best location for the intermediate pas-' sage 20 may not be in the middle of the vane, but the two subdivisions of the vane may be unequal in size, the proportionsbeing subject to experimental determination for'any The subdivision of a vane should not be carried too far, since additional losses will .be imposeddue to the expansion loss as the water leaves the discharge edge of each subdivision. The advantages to be secured will in many instances more than oflset the additional losses, and a subdivision of each vane into two parts will be particularly advantageous in high specific speed turbinesand pumps.

In the modification illustrated in Fig. 8 the vanes 21, 22,23 and 24 are so positioned that they will together have the minimum retarding efiect upon the flow and maximum useful thrust in the direction of rotation.

As one way of finding the best relative positions of the vanes of a group relatively ad- - justable hubs 31, 32 may be provided carrying sets of blades V V respectively arranged to alternate with each other as shown give different relative positions of the vanes as by shifting the group of vanes 22, 24 (Fig.

ranged in groups of inner blades B and outer blades B inclined with relation to each other.

, in Fig. 9. The two hubs will be rotated to In Fig. 11 the runner or propeller P has groups of dissimilar blades the forward auxiliary blades 13: being shorter than the rear main blades B By this relative grouping of the vanes or blades of the rotor the flow through the rotor is made smooth and even and eddies and wasteful disturbances are avoided; thereby reducing theloss of head and improving the efliciency of the energy conversion particularly when operating under'conditions of speed and head or capacities different from the normal designed conditions.

When operating under other conditions than normal such that an eddy would-be formed behind a blade of ordinaryform, by subdividing the blade the formation of a single large eddy will be prevented and the eddy will be broken up by the subdivision of the vanes into a number of smaller eddies, absorbing much less energy, and the better guidance provided for the water in the passages formed between the subdivisions will considerably reduce the tendency toward vanes similar to each other and disposed in said conduit, and a second circular series of vanes having hydraulic cooperation with and disposed between the vanes of said first series, said econd series also having their entrance edges axially displaced with relation to the entrance edges of the vanes of said vfirst series and means adapted to impart whirl tothe fluid flowing to said rotor.

2. A hydraulic machine comprising a flow conduit-having guiding walls and a rotor having ahub carrying a circular series of vanes similar to each other and disposed in said conduit, and a second circular series-of vanes having hydraulic cooperation with and disposed between the vanes of said first series, said second series also having their en,-

tranceand discharge edges axially displaced. with relation to the entrance and dischargm edges, of the vanes of said first series and means adapted to impart whirl to the fluid flowing to said rotor. r

. 3. A h draulic machine comprising a flow 5 conduit having guiding walls and a rotor having a hub carrying a plurality of similar vanes in a circular series around said hub" said similar vanes each of said intervening vanes being relatively closely spaced to one of the adjacent vanes.

5. A hydraulic machine comprising a flow conduit having guiding walls and a rotor having a hub carrying a plurality of similar vanes in a circular series around said hub in said conduit, and vanes intervening between said similar vanes each of said intermediate;

vanes being relatively closely spaced to its preceding adjacent vane.

6. In a runner for a hydraulic turbine or termediate vanes adjacent to the rear surfaces of said similar vanes to control the flow along said surfaces.

:7. In a rotary impeller or runner, a rotor.

hub carr 'ng a circular series of similar I vanes and a plurality of intermediate vanes inclined with relation to said similar vanes so as to'guide the flow along lines inclined thereto. Y

'8. A hydraulic machine comprising a flow conduit having guiding walls, a rotor having a ub carrying a circular series of equally sp ced vanes, and a second circular seriesof e ally spaced vanes in said conduit between t e vanes of said first series, each vane of the second series being spaced nearer to the rear surface of a preceding vane ofthe first series than to the front surface of the following vane of"said first series.

9. In a rotary impeller or runner the combination with a circular series of equally spaced vanes, of ,a second circular series of equally spaced vanes between the vanes of said first series, each vane of the second series being inclined with relation to a corresponding vane of the first series and spaced nearer to the rear surface 'of said corresponding vane than to the front surface of the following vane of said first series. I j

ll). In a rotary impeller or runner thecombination with a circular series of equally spaced vanes, of a second circular series of equally spaced vanes between the vanes of said first series, each vane of the secondseries being inclined with relation to a.co rrespond- .inclined with respect to said vanes to pro- .pump, a plurality of similarvanes and in-' in the said first series and offset inposition ing vane of the first series and spaced nearer to the rear surface of said corresponding vane than to the front surface of the following vane of said first series, the vanes of one series being of shapes different than the vanes of the other series.

11. In a rotary impeller or runner the combination with a series of vanes, of auxiliary diffuser guides between said vanes inclined with respect to said vanes to provide a'passage enlarging in the direction of flow.

12. In a rotary impeller or runner a series of vanes forming passages between them and guides forming diffusers between-said vanes Eide a passage enlarging in the direction of.

13. In a rotor for a hydraulic turbine or pump the combination with a circular series of equally spaced blades, of a second series .85. of blades between the blades of said first series and positioned with respect to the blades of said first series so as to provide between successive blades difiusing and 'acceli crating passages one of which follows the Z other in "alternating succession around the runner. 14. A hydraulic machine comprising a flow I conduit having guiding walls and a rotor having a hub carrying a plurality of series of blades in said conduit, the blades in one series being similar to each other in form and position and equally spaced, but the blades in a second series being dissimilar in formto those mo with respect to t-he'first series so as to subdivide unequally. the spacing of the first series. q g 1 15. In a rotary runner for a hydraulic turbine or ump, a rotor hub carrying a series of 1 similar lades equally spaced around the cir-' cumference and a series of subsidiary blades of smaller breadth measured in the direction of flow, said subsidiary blades being closer to the surfaces of reduced pressure of the first series and more distant from the pressure surfaces ofthe first series. r 16. In a rotatable runner for a hydraulic turbineor pump, a hubxand. a plurality of groups of vanes thereon, the vanes of each group being offset with respect to each other "circumferentially and in the direction of the axis of rotation, and the drivin face of the leading vane of each group bemg directed toward the rear face of the succeeding vane.,

17. In a rotatable runner for a hydraulic turbine or pump, a hub and a plurality of groups of vanes thereon, the vanes of each group being offset with respectto each other circumferentially and in the direction of the axis of rotation, and the driving face of the leading vane of each group being directed toward the rear face of the succeeding group.

. 18:. In a. rotatable runner for a hydraulic tlll'blllBOI pump, a hub and a plurality of group being offset with respect to each other 'circumferentially and in the direction of the groups of vanes thereon, the vanes of each axis of rotation, and the driving face of the leading vane of each group being directed to- Ward the rear face of the succeeding vane,

said vanes not being in the same spiral sur face.

19. In a rotatable runner for a hydraulic turbine or pump, a hub and a plurality of groups of vanes thereon, the vanes of each group being offset with respect to each other circumferentially and in the direction of the axis of rotation, and the driving face of the leading vane of each group being directedtoward the rear face of the succeeding group,

said vanes not being in the same spiral surface.

20. A hydraulic turbine comprising in combination means forming a passage turning from radial to an axial direction, and a runner disposed in the axial portion of said passage for receiving an axial flow and having'a hub carrying a circular group of vanes substantially similar to each other, and a second group of vanes between the vanes of said first p, dis osed so as to control the flow along the bac: surface of the vanes adjacent the discharge side of saidrunner. c

- 21. A hydraulic turbine comprising in combination means forming a passage turning from a radial to an axial direction with a transition spacg therebetween, and a runner' disposed in the axial passage having a hub carrying a circular group of vanes and auxiliary vanes between said other vanes, and means associated with thefiow passage for imparting a whirling motion to the flow entering the transition space. a

22. A hydraulic turbine comprising in combinition means forming a passage turning fro a radial to an axial direction with a tran itio'n space therebetween, and a runner dispised in the axial passage having a hub carrying a circular group of main vanes and auxiliary vanes between said main vanes for controlling the flow along the back surface of said main vanes adjacent the discharge side of said runner, and means associated with the flow passage for imparting a whirling motion to the flow entering said transition space. V 23. A hydraulic turbine comprising in combination means forming a passage turning from a-radial to an axial direction with a transition space therebetween, and a runner disposed in the axial .passage having a hub carrying'a plurality of circular groups of vanes, the entrance edge of the respective groups being axially offset with respect to each other, and means associated with the flow passage for imparting a whirling motion to the flow entering said transition space. Y

24. A hydraulic turbine comprising in combination means forming a passage turhing said groups of vanes being relatively from a radial to an 'axial direction with a transition space therebetween, and a runner the radial portion of said passage whereby a whirling component is adapted to be imparted to the flow entering said transition space.

v 25. Ahydra lic turbinecomprising in combination means forming a passage turning from a radial to an axial direction, and a runner disposed in the axial ortion of said passage for receiving an axial ow and having a hub carryinga circular group ofvanes substantially similar to eachother, and a second group of vanes between the vanes of said first group, said groups of vanes being relatively disposed so as to control the flow along the back surface of the vanes adjacent the discharge side of said runner, and a discharge passage leading from said runner and enlarging in the direction of flow thereby to decelerate fluid discharged from said runner.

26. A hydraulic turbine or pump comprisingin combination means forming a flow passage, and a rotor disposed therein andhaving a hub provided with groups of co-operating vanes, the center line of each group being inclined with respect to the rotor axis and cer-. tain of the vanes in each group having relatively, axially displaced entrance edges.

27. A hydraulio turbine or pump c0mpri sing in combination means forming a flow passage, and a rotor disposed therein and having a hub provided with groups of co-operating vanes, each roup having a main vane and a plurality of auxiliary vanes which succes-' sively have a shorter dimension in the direction of flow than an adjacent vane of 'the group.

28. A hydraulic turbine or pumpcompris ing in combination means forming a flow passage, and a rotor disposed therein and having a-hub provided with groups of co-operating vanes, each vane in agroup being shorter than its succeeding vane in said group, and each vane being disposed in advance of its succeeding vane and having-its entrance and discharge edges disposed substantially within the axial limits-of the corresponding edges of said suece'edingvane, and the vanes in each' 1 group being inclined with respect to each other so that passages enlarging in the direction of flow are formed therebetween.

.29. A hydraulic turbine comprising in combination means forming a passage turning from a radial to an axial direction with a transition space therebetween, and a runner I disposed in the axial passage having a hub carrying a plurality of circular groups of unshrouded vanes, the entrance edge of the respective groups being axially offset with respect to each other, and means associated with the flow passage for imparting a whirling action to the flow entering said transition space. i

30. A high specific speed propeller typehydraulic turbine or pump comprising in combination means formin a flow passage, and a rotor disposed therein and having a hub provided with groups of cooperating vanes, the center line of each group being inclined with respect to the rotor axis and certain of the vanes' in each group having relatively axiall displaced entranceed es.

L WIS FERRY MOO Y.

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