US2735647A

US2735647A - duport

Info

Publication number: US2735647A
Authority: US
Priority date: 1950-06-24
Publication date: 1956-02-21
Anticipated expiration: 1973-02-21
Also published as: FR1040578A

Description

w 1 Me Feb. 21, 1956 p, uPo -r 2,735,647

IMPULSE TURBINE ARRANGEMENTS Filed June 20, 1951 2 Sheets-Sheet 1 INVENTOR. fi'erm Ju Mr/ P. DUPORT IMPULSE TURBINE ARRANGEMENTS Feb 21, 1956 2 Sheets-Sheet 2 Filed June-20, 1951 P/F/O/x 4/?r INVENTOR. fi'erre jaflaf/ [ITTUIEIVEY United States Patent 9 F IMPULSE TURBINE ARRANGEMENTS Pierre Duport, Grenoble, France, assignor to Etablissements NEYRPIC, Grenoble, France, a corporation of France Application June 20, 1951, Serial No. 232,495

Claims priority, application France June 24, 1950 6 Claims. (Cl. 253-140) The present invention relates to hydraulic impulse turbines of the vertical axis type, and particularly to the arrangement of the nozzles which direct the water toward the buckets on the wheel of such a turbine.

In known arrangements of impulse turbines having vertical axes, the nozzles are uniformly spaced around the axis of the machine. That is to say, the angle between two consecutive nozzles is equal to the quotient of 360 degrees divided by the number of nozzles.

The present invention comprises the disposition of the nozzles of a vertical axis impulse turbine according to a non-uniform spacing adapted to the conditions of the installation.

In conventional impulse turbines, the uniform spacing of the nozzles results in a very wide spacing and a large angular diiference between the directions of the nozzles. Under these conditions, the distribution of water from the supply conduit to the different nozzles cannot be made without one or more long runs of piping and substantial changes in the direction of the flow.

In accordance with the present invention, the nozzles are positioned close to one another and concentrated within a limited angle about the axis. If the position of the machine is suitably chosen with respect to the direction of flow of the Water supply, this arrangement permits a reduction of the length of the piping and of the changes of direction imposed upon the water. This results in a reduction in the cost and in the space requirements of the water distributor, and opens up interesting possibilities for improving the conditions of flow within the distributor and nozzles.

The disposition of the nozzles and of the distributor in accordance with the invention allows a provision of a sector which is completely open and sufiiciently large to permit the easy lateral passage of the rotor during dismounting thereof. In most prior art arrangements, it is necessary to lower the rotor sufficiently to pass by the distributor in order to dismount it. Such a lowering of the rotor may be avoided by the use of the present invention.

In conventional turbines, the uniform spacing of the nozzles eliminates substantially all lateral reaction on the bearings, which are then simply guide bearings. It is known that in those cases where the bearings of the machine are not loaded, the rotor may be the source of nutatory vibrations. On the contrary, in turbines constructed in accordance with the invention, the positions of the various nozzles may be chosen in a fashion to produce a horizontal reaction on the turbine shaft having a direction and a value chosen in advance. Furthermore, there is always a sector of the bearing upon which there is no reaction, regardless of the number of nozzles in operation. In accordance with the invention, this unloaded sector of the bearing is provided with a lubricantsupply by any suitable means.

It is very desirable, in order to obtain absolutely vibrationless operation of an impulse turbine, to make sure that the angle between two nozzles is not a multiple of the angle between two successive buckets on the turbine rotor.

In conventional vertical axis turbines, it is sometimes impossible to obtain this condition without varying the number of buckets, because the angle between two nozzles is determined by their uniform spacing. It may then become necessary to use a number of turbine buckets which is not the optimum number corresponding to the specific speed of the machine. On the contrary, in a structure built in accordance with the invention, it is always possible to select the angles between the nozzles so that the above stated condition is satisfied.

For example, in the case of a turbine having four nozzles and twenty-four buckets (15 apart), the angles a, B, 'y, and 6 of the four nozzles, measured from the axis of the first nozzle as a datum of reference, may be:

Nozzle No. 1: a=0

0 15 Nozzle No. 3: 7 10 15 2 15 Nozzle No. 4: 6=k 15-3 k, k and k" being whole numbers. The addition of the fractions prevents the respective angles from being multiples of 15.

The figures in the annexed drawings show, by way of example, two arrangements of vertical axis impulse turbines constructed in accordance with the invention, compared to corresponding structures in conventional turbines.

Fig. 1 is a schematic plan view of an installation of a conventional vertical axis turbine having two nozzles.

Fig. 2 is a schematic plan view of a turbine structure built in accordance with the invention for the same installation as illustrated in Fig. 1.

Fig. 3 is a fragmentary view showing a bearing structure which may be used with the turbine of Fig. 2.

Fig. 4 is a schematic plan view of a conventional vertical axis turbine installation having four nozzles.

Fig. 5 is a view similar to Fig. 4, showing a modified form of the present invention adapted for the same type of installation as Fig. 4.

In Fig. 1, the turbine rotates on a shaft 9 located within a casing 10 which forms a supporting frame for the generator (not shown) situated above the turbine. Two

nozzles

11 and 12 project into the casing at diametrically opposite points. The elbows immediately upstream from the nozzles and the pipes connecting the elbows with the supply conduit 13 are located in the horizontal plane of the runner 14 of the turbine. A safety cut off valve 15 is connected in the supply pipe 13 ahead of the branch connection 16.

The arrangement shown in Fig. 1 requires, for a hydroelectric station having several turbine and generator units, a distance D between the axis of runner 14 and the axis of the runner 14 of the next unit and a spacing L between the lateral walls of the station.

Fig. 2 shows the same installation as modified in accordance with the present invention. In Fig. 2, the water flows through a branch connection 16a and thence through a straight pipe 17 and an elbow 18 to a nozzle 11a and through a straight pipe 19 and an elbow 20 to a nozzle 12a. The

nozzles

11a and 12a are of the conventional needle valve type and are respectively provided with needle adjusting mechanisms 11b and 12b. It may be observed that the

nozzles

11a and 12a are close together as compared with the

nozzles

11 and 12 of Fig. l. The pipes connecting the nozzles to the branch Patented Feb. 21, 1956 connection 16a are much shorter than the corresponding pipes of Fig. 1. Furthermore, fewer and less extensive bends are involved, at least-in the case of nozzle 12a. Thetpiping extending between-nozzler12a; and connec-. tionzilfia'isvery considerably reduced in rlength'ras :compared to the corresponding piping of Fig. 1. The weight and cost of 'the piping are correspondingly reduced.

.The'space requiredfor the installation-is also reduced. It will benoted that-the dimensions 'Da. and La are no more than about four-fifths of=the dimensions D and L, respectively.

The reduction in space reduces the cost of the supporting structures, and also the cost of. certain accessories, such'as the traveling cranes necessary forumaintenance.

.In Fig. 3 there is shown a bearing structure forv receiving the lateral thrust deliveredzto the shaft 9 by the jets :of water issuing. from

nozzles

11a and 12a and impinging on the turbine runner. The arrows 11c and 120 represent the thrust due -'to nozzlesll and 12, re-

spectively. Their resultant: is shown at. R.

The shaft 9 is journaled in a bushing 21 having a thickened portion on the side which opposes the resultant force R. This bushing 21 is supported by a frame member 22 which is also made heavier on that side. Diametrically opposite the direction of resultant R, the bushing 21 is apertured to receive a lubricant supply conduit 23. This sector of the bushing is substantially unloaded and may be .apertured'to' receive the conduit 23 without adversely affecting its bearing functions.

In Fig; 4 thereis shown :an impulse turbine having a vertical axiswith four nozzles 24,. 25, 26 .and 27, spaced conventionally at 90 from one another and supplied with water through a pipe 28 leading to a distributor 29 located in the plane of .the rotor. For a hydroelectric stationincluding several units, this arrangement requires a distance D' between the units, and a spacing L' between the walls of the station.

For a vertical impulse turbine of the same power and having four equivalent jets, the distribution of themjectors in accordance with the present invention would be that represented in Fig. 5.

The orientation of the supply pipe 28 is the same as in Fig. 4, but the four

nozzles

24a, 25a, 26a, 27a are concentrated within a little. more than one-half theperiphery of the rotor. The angle through-which the water for each nozzle must be turned to reach the nozzle is substantially reduced for. all the nozzles except 24a. The distributor 29a is substantially shorter than the-distributor 29.

.The arrangement of Fig. provides the following adr vantages over that offFig. 4:

l. A reduction of the distance D'a between units to approximately i of D', and a reductionof' the length L'a to. approximately 21 .of L.

.2. .Aireduction of the weight andconsequently of the cost of the "distributor 29a.

3. The rotor of the turbine may be dismounted laterally by moving it in the direction of the arrow A in Fig. 5.

It is easy tov see that by varying the direction of the water supply pipe 28, it. is possible to obtain the maximum:

reduction of L'a and of Da. In the case of Figs. 1 and 4, theuniform-spacing of the jets-determines the spacing D and L, whatever may bathe; orientation of the water supply pipe.

"In accordance with the invention, it is essential that all the-nozzles be located in a group about the periphery of .the turbine with thenozzles unequally spaced in such a manner that the angle, exclusive of theangle occupied by the group, between. the. axes of. the two. nozzles at theendszof. thegroup, isgreater than wh rsam s heavmb ra fimu lumberwords, the peripheral angle that is occupied bythe group itself,

measured between the axes of thevnozzles at the ends of the group, must be less. than It is preferable that the excluded angle be free and laterally unobstructed by any nozzle or distributor structure, and that it be large enough to permit lateral removal of the turbine runner throughthe unobstructed space.

Furthermore, according to the invention, thearrangement results in reducing subtsantially the importance of the housing and the structures supporting the-nozzles.

I claim:

1. In an impulse turbine, a shaft rotatable on a vertical axis, a runner fixed on saidshaftfor rotation therewith, bearing means engaging said shaft for receiving forces acting on said shaft transversely of said vertical axis thereof, at least three nozzles eachdirectedtangentially of said runner and unsymmetrically dism'buted'aboutthe periphery of said runner-in-unequally spaced relation to each other within a peripheral angle between the extreme nozzles that is less than the corresponding angle between said extreme nozzles for uniform distribution of 'said' nozzles about said axisso that water 'jets discharged through said nozzles produce a resultant "force-in apredetermined direction transversely of said shaft axisgsaid bearingmeans being disposedto oppose said'force acting in said=direction.

2. -An impulse turbine as defined in claim -l,-including means for supplying lubricant to said bearing means at a point substantially diametricallyopposite the point on said bearing means toward which said resultant lateral force is directed.

'3. In an impulse turbine having a 'runner'rotatable on avertical axis, at least three'noz'zles distributed peripherally"unsymmetrically about said axis and-directed tangentially of said runner, said nozzles being 'disposed in unequally spaced relation to each other within a limited peripheral angle about said axis between the extreme nozzles that isless than the corresponding-peripheral angle between said extreme nozzles for uniforrndistribution of said nozzles about said axis.

4. In an impulse turbine having a runner rotatable. on a vertical axis, at least three nozzles each directed ftangentially of said turbine runner, said nozzles being distributed peripherally unsymmetrically andin unequally:

said axis, and a water distributor conduit extending:

about said axis generally in said limited. peripheral angle and connected to said nozzles forsupplying water thereto, the complementary portion of said periphery excluding. said limited angle being unobstructed by said nozzles-or said distributor and providing space so that said runner may be-dismounted by movement laterally of the axis thereof through said unobstructed complementary'portion of' the periphery.

-5. In an impulse turbine having a :runner rotatable. on a vertical axis andhaving a plurality of runner buckets.

spaced uniformly peripherally on said runner about said axis, at least three nozzles each directed tangentially of the periphery ofsaid runner toward said buckets thereof, said nozzles being distributed peripherally unsymmetrically about said axis of rotation and in unequally spaced relation to each other about saidaxisof said runner Within a limited peripheral angle. between the extreme.

nozzles that is less than the corresponding peripheral angle between said extreme nozzles :for uniform distri:

bution of said nozzles about said axis, the respective an glesv about .said .axis. between any nozzle and. the other nozzles within said limited peripheral angle being different from the product of an integer and the angle between the respective buckets on said runner about said axis.

6. An impulse turbine as defined in claim 5 in which said limited peripheral angle between the extreme nozzles is less than 360 minus References Cited in the file of this patent UNITED STATES PATENTS Des Brisay Sept. 18, 1888 Doolittle Jan. 22, 1895 Biermann Dec. 17, 1895 Bancroft Apr. 28, 1914 Christensen Jan. 5, 1915 Moody Sept. 23, 1930