US1341859A - Hydraulic turbine - Google Patents

Description

L. F. MOODY.

HYDRAULIC TURBINE.

APPLICATION FILED MAY 28. I919.

.INVENTOR I M; Z

ATTORNEYS L. F. MOODY.

HYDRAULIC TURBINE.

APPLICATION man MAY 28. 1919.

Patented June 1, 1920.

3 $HEETSSHEET 2.

INVENTOR '5". M

ATTORNEYS L. F. MOODY.

HYDRAULIC TURBINE.

APPLICATION FILED MAY 28. I9I9.

3 SHEETS-SHEET 3- Z ATTORNEYS. H

. Patented June 1, 1920.

PATENT OFFICE.

LEWIS FERRY MOODY, 0F PHILADELPHIA, PENNSYLVANIA.

HYDRAULIC TURBINE.

Specification of Letters Patent.

Application filed May 28, 1919. Serial No. 300,412.

To all whom it may concern Be it 'known that I, LEWIS 'F. MOODY, a citizen of the United States, residing at Philadelphia, in the county of Philadelphia and State of Pennsylvania, have invented certain new and useful Improvements in Hydraulic Turbines, of which the following is a spoolfication.

The principal object of my invention is to provide a new and advantageous construction for the stay vanes and associated struc- 'ture in the casing or entrance conduit of'a hydraulic turbine. In the accompanying drawings, I have illustrated two specific em bodiments of the invention. After these have been considered, I will point out some of the advantages of my invention and what may be accomplished by practice thereunder. I now proceed to describe the two particular embodiments shown in the drawings. It will be understood that modifications may be made within the scope of the invention.

Referring to the drawings, Figure 1 is a section on the turbine axis andon the line 11 of Fig. 2. Fig. 2 is a horizontal transverse section on the line 22 of Fig. 1 to reduced scale;

Fig. 3, showing a modification, is a section f ontaining the axis on the line 33 of l ig. 4 is a horizontal section approximately on the line 4--4 of 3;

Fig. 5 is another section containing the axis and taken on the line 5-5 of Fig. 4.

' In the drawings, I have followed the practice, somewhat common among turbine draftsmen, of bringing certain elements along their respective circumferences into the plane of an axial section.

Referring to Figs. 1 and 2, the turbine casing is shown with its runner removed from the space 11, above which is the head cover 13, and below is the draft tube section 12. On the section 12 rests the lower distributer plate 15 with bearings for the pintles 16 of the adjustable gates 17 which are on respective shafts 19 controlled from a governor, not shown, by the gate levers 20. The upper distributer plate is designated as 18.

The supply conduit 21 is of spiral form with its wall 22 in sections fastened together by circumferential flanges 23. The casing 22 is open around its inner side toward the runner between the upper flange 24 andthe lower flange 26. The flanges 23 are strengthened at 25 and 27 as indicated in the drawings.

Between the annular edge portions 24 and Patented June 1, 1920.

nected by end walls 39 and intermediate ribs I 40, and similarly for the base 32 and lining wall section 31. Thus it will be seen that the stay vanes are. cast in units with one vane and its crown and base to each unit. These units are assembled, independently of each other, between the flanges 24 and 26 and fastened thereto by the stud bolts 33 and 34. A slight clearance is left between the consecutive heads and bases around the turbine as indicated at 36. Accordingly, the only machine work that has to be done on the stay vane sections (besides drilling and tapping the bolt holes) is to face the horizontal top and bottom fitting surfaces where the heads 28 and 32 are bolted to the flanges 24 and 26.

The modification shown in Figs. 3, 4 and 5 has the inflow conduit formed of reinforced concrete walls. In this case the stay vane sections with their heads are cast integrally, but the heads are more widely spaced apart around the turbine than in the form shown in Figs. 1 and 2. 'When the concrete walls 22', 24 and 26' are made, the anchor bolts 33' and 34' are embedded therein, and the casing reinforcement is arranged in any suitable manner to cooperate with these anchor bolts so as to transfer the stress from the reinforcement to the stay vanes-30 and the turbine structure. The stay vane sections are positioned by assembling them with the pit liner 43 and draft tube liner 12', and the concrete walls are formed up around them, the concrete filling the spaces between the successive heads 28' and 32 as indicated at 41 in the drawings. The hollow spaces 37 and 38 between the head 28', the wall 29 and the pit liner 43, and between the head 32', the wall 31' and the draft tube liner 12' are also filled up with concrete.

One of the problems in designing the casing in a hydraulic turbine is that of supporting the walls of the casing against the internal pressure of the contained water.

Any section containing the axis such as the section of Fig.1 shows that the casing has the form of a pipe with one rtion of each circumference cut away at t e. oint where the water enters the turbine gui e vanes and runner. In order to carry the tension across this space due to the pressure of the water within, it is necessary to sup 1y tie members or stays of some sort. Besi es carrying the tension due to the internal water pressure in the casing, thesestays must also be capable of acting under certain condltions as compression members or struts to support the weight of the upper portion of the cai ing and the superposed parts, such as an electric generator. In low head plants as a rule, the stay vanes act mainly as struts. In high head plants, they evidently act as struts when the turbine is idle and the conduits empty of water, but in normal operation or when shut down with the conduits containing water under pressure, the stay vanes are subject to tensile stress. .In'most installations the stays are likely to 'be subjected to both kinds of stress in varying degree at different times.

The use of ordinary stay bolts or rods to take care of the stresses just discussed is objectionable, because they offer an obstruction to the flow. Accordingly, it has been common to cast a stay vane ring as a whole or in a small number of large sections. In accordance with this method, when the stay vane ring has been made in sections, these sections have been assembled together by means of bolts to form a complete ring and this has been machined on a .large boring mill so as-to fit with the casing, head covers,

etc. Another way has been to cast the'stay 1 vanes integrally with the rest of the casing, but this involves serious risk of leaving initial stresses in the structure by the process of casting and cooling so that the strength of the resultant casting is indeterminate.

My invention, of which examples have been disclosed in the foregoing specification, overcomes the ob'ections to the above.

mentioned methods 0 bracing the casing walls. As disclosed in this s ecification, each vane is cast integrally with a small crown section at one end and a small base section at the other end, but these sections are not intended to be bolted together and a little clearance is left between them so that there is no occasion for machine work between them. The only places that have to be machined are the plane horizontal top and bottom surfaces, which are parallel and can be readily machined without the necessity for assembling the sections in a boring mill, the operation being performed by planing a number of the sections at once on a planer or by other well known methods.

The pressure of the water within the casing not only sets up stresses in the plane of large speed ring sections.

nauseoan axial section tending to spread a art the inner edges of the casing as hereto ore discussed but it sets up stresses in a circumferential direction around the axis tending, for instance, to pull apart-the casin sections where ;bolted together as at anges 23. (Fig. 2.) When the stay vane ring has been inte ml or in sections bolted together, it has on a part of the casing wall and has been depended upon to meet these 76 last mentioned stresses to a certain extent, and hence when the ring has been in sections it has been necessary to bolt the sections strongl together. This has often been a difficult matter because of the difliculty of getting space for the bolts. By my invention the stay vane sections are not connected and all this circumferential stress is 27, in which there is ample space for the necessary bolts and the difficulty of bolting the sta vane sections together is entirely avoide Not only do I avoid the necessity for machine work between the sections by leaving a clearance between them, but I leave a clearance between the base and crown and the adjacent distributer plates, so that the only fitting to be done is on the top and bottom surfaces.

In addition to the facility of the machine work in connection with my invention, the task of casting is much simplified, because instead of casting at one time a large and 100 heavy speed ring or a large section thereof, which requires the use of cores in either case, I cast the single small sections separately, each casting being simple and easy to handle. If any vane should prove to be 108 defective, it can be rejected without involving sacrifice of an entire speed ring or a large speed ring section.

For large turbine units, my invention provides an excellent solution of the 110 problem of shipment; heretofore it has been a problem of much difficulty to ship The comparatively small sections of my invention can be readily shipped and handled.

In a turbine having a cast metal casing made in sections, the stay vane sections can be assembled in the shop in the various casing sections and then can be shipped in place in their respective casing sections. In turbines of the concrete casing type the largest piece which requires machining on a boring mill, in the type of turbines now commonly used, is the speed ring. The dimensions of this ring therefore place a limit on the size of the turbine which can be built in a shop equipped with a certain capacity of boring mill. In the design provided by my invention this limitation is removed, and it therefore becomes possible to manufacture turbines of larger size than would otherwise be possible in a shop having limited boring mill capacity.

The design shown in Figs. 3, 4 and 5 would be suitable only for very'low heads. In units of this type intended for heads of moderate amount, the stay vane sections would be spaced more closely together, and would frequently be closely spaced with merely enough clearance between them to avoid the necessity for machining the adjacent faces, as in the case of the embodiment shown in Figs. 1 and 2..

I claim 1. In combination in a hydraulic turbine, a circumferential series of stay vanes standing between the casing walls above and below, said series being made in a large number of sections and each section comprising a crown part and a base part and a small number of vanes, each section being held in place in the series by having its crown part and base part respectively fastened to the turbine structure above and below.

2 In combination in a hydraulic turbine, a circumferential series of stay vanes standing between the casing walls above and below, said series being made in a large number of sections and each section comprlsing a crown part and a base part and a small number of vanes, each section being held in place in the series by having its crown part and base part respectively fastened to the turbine structure above and below, and said vanes serving as struts to sustain the weight of the upper wall and as tie members to hold V said walls against pressure within the cas- E. In combination in a hydraulic turbine, a circumferential series of stay vanes standing between the casing walls above and below, said series being made in a large number of sections, and each section consisting of a single casting comprising a crown part and a base part and a small number of vanes, each section being held in place in the series by having its crown part and base part respectively fastened to the turbine structure above and below.

4. In combination in a hydraulic turbine, a circumferential series of stay vanes standing between the casing walls above and below, said series being made in a large number of sections entirely separated from one another by clearance spaces and each section comprising a crown part and a base part and a small number of vanes, each section being held in place in the series by having its crown part and base part respectively fastened to the turbine structure above and below.

5. In combination in a hydraulic turbine, a circumferential series of stay vanes standing between the casingwalls above and below, said series being made in a large number of sections and each section consisting of a single casting comprising a crown part and a base part and a small number of vanes, said crown and base parts'having respectively upper and lower parallel surfaces machine finished and fastened to the turbine structure.

6. In combination in a hydraulic turbine, a circumferential series of stay vanes standing between the casing walls above and below, said series being made in sections, each section comprising a crown part and a base part and a single vane between them, each section being held in place in the series by having its crown part and base part respectively fastened to the turbine structure above and below.

7. In combination in a hydraulic turbine, a circumferential series of stay vanes standing betweenthe casing walls above and below, said series being made in sections, each section consisting of a single casting comprising a crown part and a base part and a single vane between them, each section being held in place in the series by having its crown part and base part respectively fastened to the turbine structure above and below.

8. In combination in a hydraulic turbine, a circumferential series of stay vanes stand= ing between the casing walls above and below, said series being made in sections, each section consisting of a single casting comprising a crown part and a base part and a single vane between them, each section being held in place in the series by having its crown part and base part respectively fastened to the turbine structure above and below, said sections being assembled with clearance spaces left between adjacent sections.

9. In combination in a hydraulic turbine,

a conduit around the runner and opening toward it, and a circumferential series of stay vanes standing across between the walls thereof, said series of vanes being made in a large number of sections with a small number of vanes and a base part and a crown part in each section, said base and crown parts being fastened respectively to the lower and upper inner edges of the conduit wall.

10. In combination in a hydraulic turbine,

a conduit around the runner, and a circumferential series of stay vanes standing across between the walls of the conduit and fastened thereto, said series of vanes being made in a large number of sections with a small number of vanes in each section.

11. In combination in a hydraulic turbine, a conduit around the axis adapted for a large component of radial flow and having an upper wall and a lower wall with an opening between them toward the axis, and means to stay the walls at their edges adjacent to this opening, said means consisting of a circumferential series of vanes in sections with a small number of vanes in each section and a common base and a common crown for each section, said base and crown for each section being fastened directly to the said edges of the walls.

12. In combination in a hydraulic turbine a series of independent stay vane sections, each having a crown part and basepart integral with the vane part but separate from and free of contact with or attachment to the base parts and-crown parts of adjacent sections.

13.. In combination in a hydraulic turbine a series of independent stay vane sections, said sections each having a crown part and base part separate from and free of contact with or attachment to the base parts and crown parts of adjacent sections.

14. In combination in a hydraulic turbine having an inlet space surrounding the turbine runner, a series of separate stay vane sections connected at both ends to the portion of the turbine structure on either side of said inlet space but free of contact with or attachment to each other.

15. In combination in a hydraulic turbine having an inlet space'surrounding the turbine runner a'series of separate stay vane sections connected by parallel faced surfaces on both ends to the portions of the turbine structure on either side of said inlet space but free of contact with or attachment to each other.

16. In combination in ahydraulic tur-- bine, a circumferential series of stay vanes standing between the casing walls above and below, said series being made in a large number of sections and each section comprising a crown part and a base part and a small number of vanes, each vane. bein formed to guide the water with a tangentia l component of motion, each section being held in place in the series by having its crown part and base part respectively fastened to the turbine structure above and below.

17. In combination in a hydraulic turbine, a circumferential series of stay vanes standing between the casing walls above and below, said series being made in a large number of sections and each section comprising a crown part and a base part and a small number of vanes, each vane being oblique to the corresponding radius, each section being held in place in the series by having its crown part and base part respectively fastened to the turbine structure above and below.

18. In combination in a hydraulic turbine, a circumferential series of stay vanes standing between the casing walls above and below, said series being made in a large number of sections and each section comprising a crown part and a base part and a small number of vanes, each section being clear of contact with and of direct attachment to other sections.

19. In combination in a hydraulic turbine, a circumferential series of stay vanes standing between the casing walls above and below, said series being made in a large number of sections and each section comprising a crown part and a base part and a. small number of vanes, each section being clear of direct stress communication with other sections.

LEWIS FERRY MOODY.

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