US2041570A

US2041570A - Turbo-machine

Info

Publication number: US2041570A
Application number: US699964A
Authority: US
Inventors: Reiffenstein Manfred
Original assignee: Individual
Current assignee: Individual
Priority date: 1933-07-22
Filing date: 1933-11-27
Publication date: 1936-05-19
Anticipated expiration: 1953-05-19

Description

May 19,1936. M. REIFFENSTEIN TURBO MACHINE Filed Nov. 27,1933 4 Shoots-Sheet 1 y 1,936- M. REIFFENST'EIN 2,041,570

TURBO MACHINE Filed- Nov. 27, 1933 4 Sheets-Shee't 2 appropriate linkage for Patented May 19, 1936 JPATENT OFFICE TURBO-CHINE mnma Reiflenstein. mm, m

Application November 27, 1933, Serial No. 899,964

In Austria 1: Claim. (Cl.v 253-124) I In reaction hydraulic turbines of the open flume'type with adjustable runner blades (Kaplan turbines) usually a conventional adjustable speed ring is provided the wickets of which are adjusted simultaneously with the runner blades by the efiicient control of the turbine.

In some types of construction the adjustable feature of the speed ring wickets have been dispensed with and the speed ring is only made up by fixed guide vanes. In this case the control is effected only by adjusting the runner blade If the water is led to the runner from a penstock or intake by means of a scroll case a speed ring with adjustable vanes is also generally provided for at the scroll outlet.

' In another type of construction a single control device is provided for inthe scroll in the first part of the spiral path of the water. This control device may be adjusted simultaneously with the runner blades for an efiicient control of the turbine.

In these different types of construction known tothe art the size and weight of the speed ring or of the control device and the corresponding actuating force increase rapidly with the size of the turbines so that the construction is more diflicult and costlier.

In view thereof it has been already advocated to dispense with any type of adjustable or fixed speed ring and to lead the water to the runner by a way of a conventionally shaped scroll case of appropriate size. However this conventional type of scroll case gives a definite angle of admission into the runner and gives smooth flow conditions or if the speed of the turbine varies, no control" being effected in adjusting the runner blades, or if the head varies, the setting of the runner blades being unaltered the speed of the unit being maintained for instance by a generator driven by the turbine, this generator being tied at synchronous speed to a power system.

. With varying hydraulic. conditions in the turbine the inlet angle to the runner must be altered to sustain good efiiciency. The best efllciency inlet angle will not correspond in every case to that imparted by the scroll so that the inlet con- 5 ditions to the runner are inadequate bringing turbulence and eddies at all but one condition. Therefore this possibility of using a plain scroll caseof the conventional type without speed ring has not been found suitable in practice. I The above difi'iculties are overcome according to the present invention, which relates to a turbo-machine with a scroll case without speed ring or control devices in the inside, the said scroll case being fully filled with the fluid at every working condition and at all the diflerent working conditions will let the flow adjust itself so as to reach the runner with different angles, whereby the fiow conditions are as efliclent as those obtained with anadjustable speed ring.

This 'eflect aimed at is obtained in that, in the scroll G without speed ring or control device, the space In between the spur S and the runner L is made so wide, and the last part of the spur-face so curved, that the fluid will perform one or sev- 2'5 eral revolutions in this casing according to the working conditions without eddies, cavitation or dead water spaces.

. The streams or currents 1!, 11' whirling round in the scroll meet the incoming current a: without eddies and the cross section of that current varies regularly as it whirls round toward the runner (in case of prime movers) or the discharge current 2: separates from the whirling water in the scroll 1!, 1! without shock or eddies and the cross section of the current varies regularly as it whirls round from the impeller into the scroll outlet (in case of pumps, fans or the like).

The scroll case being not provided with a control device the different working conditions will arise either by varying the head, or the speed of the runner (or impeller), or by adjusting the runner (or impeller) blades.

The scroll case according to the present invention in combination with a runner (or impeller) efllciently under certain varying conditions such as change in head at constant speed, change of speed at constant head. The efllciency \mder these conditions is maintained higher than that of the fixed type machines.

The turbo machine according to the invention with its special scroll case can also be made a dual purpose machine and can be designed to work efliciently both as a turbine and a pump.

Some modes of carrying out the invention are shown in Figs. 1 to 18 in connection with a water turbine with'runner blade control.

Figs. la. and 2a are longitudinal sections through a scroll case showing the flow in the interior thereof in diflerent working conditions. Figs. lb and 2b illustrate the cross sectional areas through which flows successively the water.

. Figs. 1c and 2c are diagrams showing the variation' in the area of the said cross sectional areas. Fig. 1d is an axial section through the scroll case illustrated in Figs. la and 2a. Figs. 3a and 3b are diagrams of the comparison of the cross sections through which passes the water during the discharge and at different working conditions. Figs. 4 to 18 illustrate constructions of scroll cases according to the present invention.

Fig. la shows the flow through a scroll case with cone-shaped side walls and plane spiral line as generatrix in a working condition corresponding to a great discharge. Fig. 1d is a cross section thereof. In these views G designates the scroll case having the centrally disposed runners entrance E, 5-8 the length of the overall edge of the spur, R the free cross sectional area between spur and transition space, A the transition space which converges toward the runner's entrance E, and L the mnner. entrance E is the radial free distance between the hub of the runner and its periphery. This length is considerably less than the length of the overall edge of the spur S. I, 2, 3, and 4 at the left hand side of Fig. 1d designate the superposed sections of the'scroll shown in Fig. la in the planes I, 2, 3, and I.

The fluid in the form of a current a: is admitted into the case at the cross section I and after describing one and a half revolutions passes to the runner L by way of the constricted transition space A, which generally is present butis not absolutely necessary. Both currents, namely the newly admitted current a: at the left and the remaining part of the current 11 at the right, meet at the right and left hand sides of the spur S by which the scrollcase is in communication with the admission part. The action of the two currents on each other, i. e. the direction in which they flow together, depends on the momentum of each current, thus the product resulting from its mass-multiplied by its speed, its mean direction and on the pressure distribution on each side of the spur or tongue. The direction of common flow is designated Z1 in Fig. la. The middle line of the spur must agree substantially to the direction Z1, in order that the spur is not, the cause at this place of any separation'of the current from the wall and of any eddying losses. The return current 1/} has to join closely to the current; over the whole width, and the side walls of the scroll case must not be unsteady at this place, in order that all current filaments act uniformly when the currents at and 1/ act on each other.

Fig. lb illustrates the cross sections I, 2, 3, 4, I, and 2' through which the fluid successively passes on its way from the entry I to the case until The length of the runner's it completely passes into the transition space A to the runner L.

Fig. 1c is a diagram showing the reduction of the area of the cross sections through which the fluid flows. F0 represents the size of the cross section of admission I. As shown in Fig. la, the water begins to go through the runner at section 3. Thus the cross section F1 in section 3 is reduced to zero during the discharge period p, which corresponds to the last revolution. The entire water flowing through F1 enters the runner during this period 9. Therefore the cross section F1 essentially determines the condition of flow in front of the runner and the angle of admission to the runner.

Fig. 2a shows the flow through the same case at another condition of working which corresponds to a smaller discharge. The fluid a: is admitted at I and passes through the scroll case.'

However the runner discharge capacity is now reduced (because for instance its vanes have been set'at a flatter angle) and therefore the entire current is again returned as back current 3/ with an increased speed and forces to the left the common direction of flow Z2. No part of the current a: has passed to the runner even after the second revolution, and the second return current 1 bears against the first return current y. Only after a further quarter of a. revolution, the incoming of the water into the runner starts at section 2" and proceeds for a whole revolution up to 2". The action of the supply current a: and the return currents y and 11' against each other depends, like in the case shown in Fig. la, on the momentum of the currents at, y, y and on the pressure. The momentum of the return currents surpasses very considerably the momentum of the supply current, because the speed of the back currents u and y is far greater than that of the supply current a: (the speeds being the reverse to the cross sections I, I, and I) and the mo- -mentum of each return current is equal to that of the supply current :22. Therefore the common direction of flow Z2 depends practically solely on the return currents. In view thereof it is necessary to sufllciently enlarge the cross section R between the spur S and the transition space A '(Fig. 1d) through which the return currents y and 11' must flow, in order to allow the passage of the return currents without losses due to throttling.

Further, like in Fig. la, the return current 11 I must lie against the supply current a: over the same width. and the direction of the last spur part S must adapt itself substantially to the direction 2:. Therefore the middle line of the spur ought turbine) or must begin with a streamline proflle (in the case of a pump).

Fig. 2b shows the cross sections I, 2, 3, l, I', 2,

3', I, I", 2", 3", 4", and I"' through which the fluid successively passes from the admission into the case until the completed discharge to the runner.

Fig. 2c is a diagram of the areas of these sections through which passes the medium. F0

designates the admission area in the section I.

It is readily seen,,that this area decreases rapidly in the

sections

2 and 3 which, as'above deaosasvo I sensed; is due to the action of the return currents y and 1 From the section I the areas remain in about the same size during a number of revolutions and vary only-by slightly decreasing undulations. The water circulating. within the scroll describing an axially unsymmetric potential flow, isalternately being accelerated (when passing the sections I and I) or retarded (when passing the

sections

2 and 2"). In order to prevent during this stage any cavitation and ed-.

dying of the fluid, the scroll case must be of av shape that the sections through which the fluid passes are varied quite gradually and that the permissible divergence ofthe current filaments is not overstepped anywhere during the period of retardation. The discharge on to the runner begins at the section 2" and takes place for an entire revolution during the discharge'period- 1:. During this period of discharge p, the cross sec- .tion F: decreases to'zero and thereby determines the flow in front of the runner and the angle of admission to the runner.

Figs. 3a and rib-illustrate the comparison between the periods of discharge 1: for the working conditions shown in Figs. la and 2a; 3a corresponding to the condition according to Fig. la,

thus. the working with a large discharge, while Fig. 3b corresponds to the condition according to Fig. 2a, thus the working with a small discharge. The rapidity of decrease of the cross sectional areas through which the fluid passes agrees to a I value, peculiar to every scroll case and which determines the entire flow infront of the runner and the angle of admission into the same. In

Fig. 3a, the cross section F1 at the beginning is approximately threetimes as large as the cross section F: at the beginning in Fig. 3b. In both' cases the speeds of flow are about alike and therefore during the period of discharge in the case of 1 Fig. 30 approximately three'times as much water enters the runner as in the case of Fig. 3b. In

consequence thereof, also the angles of admission must be far greater in the case of Fig. 81: than in the event of Fig. 3b. In the caseof Fig.

. 3a the water'makes one and a half revolutions until the discharge to the runner is terminated, while in the case of Fig. 317 three and a quarter revolutions are made. It the whole water would pass to the runner during a single revolution as it is the case in common scroll cases with speed ring, the cross sectional areas through which the water passes through the case according to Fig. la would be reduced in accordance with the curves shown indashes in Figs. 3a and 3b. The entire cross sectional area'of admission F0 would be reduced to zero in a single revolution.

However in the event of a scroll case without guide or adjusting device according to the present invention, a quite differently variable diminution of the cross sectional is theresult owing to the reaction of the runnerand the several revm lutions of the fluid caused thereby, this depending on the working conditions as illustrated in Figs. 3a and 3b and as described above. Thus it is proven, that according to the flow conditions a plain scroll case according to the present inven- I tion may be suited for a quite different diminution law and thus act on the passing fluid in quite a differentway, because other angles of admission to the runner correspond to another law of the. reduction of the cross sectional areas. Thus bythe use of the scroll case according to the present invention it is possible to design a scroll case without guide or adjusting devices and mostly water runs on water.

with variable angleof admission to the runner at different working conditions and which operates substantially like a common scroll case with adjustabl'e speed ring.

The common direction of flow Z behind the spur S is determined by the action of the currents :c,

'w and v on one another. It may greatly differ according to the pressures and extents of motion of the currents 'z, y and 11'. With respect to the geometric direction .of the last spur part, a kind of "angular deflection results to the one or the other side as it is known to obtain at the outlet edge oi the blades of aturbine runner or pump impeller, i. e. the direction of the return current 0, after leaving the spur-edge S, deviates for a certain angle from the geometrical direction of the last spur part. The flow in the scroll case is kept regular by this "angular deflection .at different conditions or working, although the pressures and velocities may greatly diner at th right'and left hand sides of the spur.

Approximately the same deviation of angle should result along the entire spur edge, as otherwise secondary vortices would be formed owing to the dlflerent directions of the velocities, which would overburden themain flow. These secondary vortices are quite similar-to the marginal vortices at the edges of the planes of flying ma-- chines or propellers.

They would upset a large part of the current and would be. very detrimental, because they would return into the main current after a revolution. The angular deviation of diflerent magnitude at different conditions' of working'without causing vortices in a scroll case according to the present invention, can

be compared with the action, which an adjusting device'in the neighborhood of the spur 8 would exert on the current. l

The flow prevailing in the scroll case according to the present invention, whereby care is taken of .the laws abovementioned, is a potential flow of low losses and eddy free, but which is not quite symmetricaround the center but oval to a greater However this flow approaches '46 friction and vortices which. are formed by any speed control' device arranged inthe interior of the scroll, are dispensed with in the scroll 'case according to the present invention. Finally also the danger of clogging up by foreign matters is reduced.

The scroll case according to the present invention may be constructed in different ways according to the chosen cross section and the path which the medium current filaments have to describe, whereby the characteristics are maintained, namely diiferent numberspf revolutions of the fluid at different working conditions and steady variation of the cross sectional areas of the case passed by the fluid whereby vortices, cavitation and the formation of dead water spaces are avoided and the currents circulating in the case unite with the admitted current without causing any eddies (or the discharged current separates causing any eddies).

Figs. 4 to 18 illustrate some further constructions used in connection with a water turbine.

Fig. 4 shows a scroll case with a plane spiral line as generatrix, rectangular cross sections of. uniform height and non-symmetric supply to the 'fromlth e current circulating in the case without runner. Fig. 5 illustrates a scroll case-with conical spiral line as generatrix and rectangular cross sections -'0f uniform height. This embodiment corresponds to the known conical speed ring. Fig.

6 illustrates a scroll case with cylindric spiral line as generatrix and rectangular cross sections of uniform height." This construction corresponds to a speed ring-with axial flow and is particularly suited for propeller turbines and axial centrifugal pumps. Fig. 7 shows a scroll case with conical ascending spiral line as generatrix and rectangular cross sections of uniform height;

and round cross sections of uniform height. Fig. '13 illustrates ascroll case with conical spiral line as generatrix, round cross sections of decreasing height and curved spur edge. Fig. 14, shows a scroll case with conical spiral line as generatrix,

rectangular cross sections of. decreasing height and bent spur' edge. Fig. 15 is a scroll case with plane spiral line 'as generatrix, rectangular cross section of decreasing height and double bent spur edge. Fig. 16 illustrates-a scroll case with plane spiral line as generatrix, round cross sections of decreasirg height and bent spur edge. Fig.

17 shows a scroll case with plane spiral line as generatrix, rectangular cross sections of decreasing height, double bent spur edge and with the lateral boundaries of the space R in the form of cone-shaped surfaces (no rotation surfaces). Fig. 18 is a scroll case with plane spiral line as generatrix oval cross sections of decreasvii ing height, oval bent spur edge and with the, lateral boundaries ofthe space R. in the form of oval cone-shaped surfaces (no rotation surfaces). In order to obtain theeifect according to the present invention it is not necessary that the middle' line of the spurpasses' between the extreme directions Z1 and Z: as long as the per- .missible limits of the angular deviation arenot overstepped.

Further it is not necessary, that the scroll case is of uniform height throughout, as shown. in Figs. 4, 5, 6, '7, 11, and 12. It may be of varying' heights as shown in Figs. 1d, 8, 9, 10, 13, 14,

15.1 17, and 1a.

It is not necessary that the spur edge is straight, as shown inFigs. 1d, 4, 5, 6, 7, 8. and.

10. It may be curved as shown in Figs. '11, 12, 13, and 16 or. itcan be bent as illustrated in Figs. 14, 15, 17, and 18. In these cases the end edge.

shaped part islwashedby the fluid at both sides part of the scroll is in the form of a spoon which projects into the admission part of the scroll case and terminates with the curved or bent spur Thereby it is essential that this spoonand over the same length.

-- The lateral boundaries of the space R. are

commonly revolution surfaces. However this is not absolutely necessary. For this object preferably any surface may be chosen, which is adequately shaped for a certain flow which is to be preferred, thus the surface being for instance cone-shaped as shown in Fig. 1'7 or oval coneshaped surfaces are used as illustrated in Fig. 18.

Also other designs may be resorted to besides the examples as described. Thereby the tradition must not be followed and the most favorable forms maybe determined from a hydraulic point of view supported by systematic experiments, whereby the principles according to the present invention are safeguarded. In view thereof that neither a speed ring, whether fixed or movable, is present in the transition space 'A to the runner, nor a single control device is provided within the scroll at the beginning of the spiral path of the fluid, it is possible to readily apply the geometrically most complicatedshapes and a hydraulically favorable shape can be chosen because no guide and control devices have to be constructed or fitted. It is not necessary that the scroll case is completely closed, and it may be left openat one side. For instance in Figs. 4 or 8 the top wall at the side can be dispensed with and the fluid passes through the scroll with a free surface.

For-strength purposes it may be necessary to arrange suitable intermediate supports in the transition space A to the runner, said intermediate supports being carefully streamline-shaped and positioned, so as to upset as little as possible the flow at all working conditions.

As already mentioned it is quite obvious that the scroll case according to the' present invention is adapted not only for turbines alone, but also for all turbo-machines. In the event of motor driven machines (centrifugal pumps and the like) all current-proceedings in the scroll case take place just in the contrary direction as described with reference to prime movers '(water tubine).

-Not only water, but any liquid, gas, steam or vapors may be used as driving agent.

It is to be noted in the accompanying claims that the'free space between the inner surface of the spur'S and the runners entrance E is the total of e the space R in Fig. la plus the transition space A. In some figures such as 5, 6, 8, 9, 11, 12, 13, and 14 the transition space may .be said to be omitted or joined with-the space R. so as to form a part thereof.

What I claim is:

1. In a turbo-machine, of high specific speed, a plain spiral casing designed to be entirely filled by the fluid at all working conditions and having a runners entrance and having a free inlet of greater cross-sectional area than that of the runners entrance, a spur whose overall edge has. a length considerably greater than the run- -ners entrance, said spur being disposed in the casing so as to provide a free space between the inner surface of the spur and the runners entrance, the casing at a point in advance of the runners entrance having a converging section, and a controllable runner for regulating the flow distribution and the performance of the turbomachine.

2. In a turbo-machine of high specific speed, a plain spiral casing designed to be entirely filled by the fluid at all working conditions and havinga runners entrance and having a free inlet of greater cross-sectional area than that of the runners entrance, the directrix of the casing being a plane spiral while the lateral boundaries thereof are in the form of plane surfaces, a spur in the casing the overall edge of which has a length considerably greater than the runners entrance, said spur being disposed in the casing so as to provide a free space between, its inner surface and the runners entrance, the casing at a point in advance of the runners entrance having a converging section, and a runner having adjustable blades which controls by different setting of its blades the flow distribution and the performance of the turbo-machine.

3. In a turbo-machine of high specific speed, a plain spiral casing designed to be entirely filled by the fluid at all working conditions and having a runners entrance and-having a free inlet of greater cross-sectional area than that of the runners entrance, the directrix of the casing .being in the form of a plane spiral while the lateralboundaries are in the form of surfaces of revolution, a spur the overall edge of which has a length considerably greater than the runners entrance, said spur being disposed in the casing so as to form a free space between itsinner surface and the runners entrance, the casing at a point of advance of the nmners entrance having a-converg ng section, and a runner having adjustable blades'which controls by diflerent setting of its blades the flow distribution and the performance of the turbo-machine.

4. In a turbo-machine of high specific speed,

', a plain spiral casing designed to be entirely filled by the fluid atall working conditions and having a runners entrance and having a free inlet of greater cross-sectional area than that of the runners entrance, the directrix of the casing being in the form ofa cylindrical-screw line while the lateral boundaries thereof are in the form of surfaces of revolution, a spur whose overall edge has a length considerably greater than the rimners entrance, said spur being disposed in the casing so as to form a free space between its inner surface and the runners entrance, the easing at a pointin advance of the nmner's en trance having a converging section, and a run- 1 n6! having adjustable blades which controls by diiferent setting of the blades the flow distribution and the performance of the turbo-machine.

5. In a turbo-machine of high specific speed, a plain spiral casing designed to be entirely filled by the fluid at all working conditions and having a runners entrance and having a free inlet of greater cross-sectional area than that of the runners entrance, the directrix of the casingbeing in the form of any desired spatially curved spiral while the lateral boundaries thereof'are in the form of surfaces of revolution, and a spin the overall edge of which has a length considerably greater than the'runners entrance, said spur being disposed in the casing so as to form a free space between its inner surface and the runners entrance, the casing at a 'point in advance of the runners entrance having a converg-v ingsection, .and. a runner having adjustable blades which controls by diflerent setting of its blades the flow distribution and the performance of the turbo-machine. j

-6. In a turbo-machine of high specific speed, a plain spiral casing designed to'be entirely filled by the fluid at all working conditions and having a, runners entrance and having a, free inlet runners entrance, said spurbeing disposed in the casing so as to form a free space between its inner surface and the runners entrance, the casing at a point in advance of the runners entrance having a, converging section, and a runner which controls by its different relative speed the flow ,distribution and the performance of the turbomachine.

7. In a turbo-machine of high specific speed, a plain spiral casing designed to be entirely filled by the fluid at all working conditions and having a runners entrance and having 'afree inlet of greater cross-sectional area than that of the runners entrance thedirectrix of the casing being in the form of a plane spiral while its lateral boundaries are in the form of plane surfaces, a spur whose overall edge has a length considerably greater than the runners entrance, said spur being disposed in the casing so as to form a free space between its inner surface and the runners entrance, the casing at a point in advance of the runners entrance having a converging section, and a runner which controls by its dlfierent relative speed the flow distributionand the performance of the turbo-machine.

, 8. In a turbo-machine of high specific speed, a plain spiral casing designed to be entirely filled by the fluid at all working conditions and having a runners entrance and having a free inlet of greater cross-sectional area than that of the runners entrance, the directrix of the casing being in the form of a plane spiral while the lateral boundaries thereof are in the form of surfaces of revolution, -a spur the overall edge of which has a length considerably greater than the runners entrance. said spur being disposed in the casing so as to provide a free space between its inner surface and the runners entrance, the casing at a point in advance of the runners entrance having a converging section, and a runner which controls by its different relative speed the flow distribution and the performance of the turbo-machine.

9. In a turbo-machine of high specific speed, a plain spiral casing designed to be entirely filled by the fluid at all working conditions and having a runners entrance and having a free inlet of greater cross-sectional area than that of the runners entrance, the directrix of the casing being in the form of a cylindrical-screw line while the lateral boundaries thereof are in the form of surfaces of revolution, a spur the overall edge of which has a length considerably greater than the runners entrance, said spur being disposed in the casing so as to provide a free space between its inner surface and the runners entrance, the casing at a point in advance of the runners entrance having a converging section, and a runner which controls by its different relative speed the flow distribution and .the performance of the turbo-machine. I

l0. A turbo-machine of high specific speed, a plain spiral casing designed to be entirely filled by the fluid at all working conditions and having a runners entrance and having a free inlet of greater cross-sectional area than that of the nmner's entrance, the directrix of the casing being of any desired spatially curved spiral while its lateral boundaries are in the form of surfaces of revolution, a spur the overall edge of which has a length considerably greater than the runners entrance, the spur being disposed in the I trance having a converging section, and a runner which controls by its different relative speed the flow distribution and the performance of the turbo-machine.

11. In a turbo-machine of high specific speed, a plain spiral casing designed to be entirely filled by the fluid at all working conditions and having a runners entrance and having a free inlet of greater cross-sectional area than that of the runners entrance, a spur in the casing having a bent spoon-like form, the overall bent and outer edge of the spur having a length considerably greater than the runners entrance, the spur being disposed in the casing so as to provide a free space between its inner surface and the runners entrance, the casing at a point in advance of the runners entrance having a converging section, and a runner having adjustable blades which controls by different setting of its blades the flow distribution and the performance of the turbo-machine. A g

12. In a turbo-machine of high specific speed, a plain spiral casing designed to be entirely filled by the fluid at all working conditions and having a runners entrance and having a free inlet of greater cross-sectional area than that of the runners entrance, a spur in the casing having a bent spoon-like form, the outer overall bent edge of the spur having a length considerably greater than the was entrance, said spur being disposed in the casing so as to provide a free space between the inner surface thereof and the runners entrance, the casing at a point in advance of the runners entrance having a converging section, and a runner which controls by its different relative speed the flow distribution and the performance of the turbo-machine.

MANFRED REIFFENSTEIN.