US1722438A - Hydraulic power plant - Google Patents

Description

July 30, 1929. MYQODY I 1,722,438 g HYDRAULIC POWER PLANT I I Filed May 26. 1920 '7 Sheets-Sheet 1 IIrI- Y Y &

Filed May 26. 1920 L. F. MOODY HYDRAULIC POWER PLANT '7 Sheets-Sheet 2 July 30, 1929. 1.. F. MOODY HYDRAULIC POWER PLANT 7 Sheets-Sheet 4 Filed May 26, 1920 L. F. MOODY HYDRAULIC POWER PLANT July 30, 1929.

' Filed May 26, 1920 7 Sheets-Sheet 5 W/w 4 i I 5514 wozvic/ugrw July 30 1929. L. F. MOODY 3 3 HYDRAULIC POWER PLANT I Filed May 26, 1920 7 Sheets-Sheet e a I J Patented July 30, 1929.

LEWIS FERRY MOODY, OF PHILADELPHIA, PENNSYLVANIA.

HYDRAULIC POVJER PLANT.

Application filed May 26,

This invention relates to hydraulic power plants and particularly to hydraulic turbine installations in connection with dams, for instance where the power house is built as a part of the dam.

The object of the invention is to provide a hydraulic turbine installation which will be strong and compact and elficient in the handling of the flow and adapted to form part of a dam and particularly of a dam subj ected to abnormal high water or flood conditions requiring an overflow of the excess water past the power station.

In many power plants, particularly'for low and medium heads, it becomes a serious problem to handle these abnormal fiood conditions, for in addition to providing for the passage of the water which is to be utilized in the turbines there must be additional discharge means capable of handling in the majority of developments quantities of water greatly in excess of the quantity normally flowing in the stream and far beyond the discharge capacity of the turbine passages. The usual method of disposing of the excess water is the provision of long spillway sections in the dam over which the water can pass. In power developments in which the power house is built a part of the dam, it often becomes difficult to provide a length of dam sufficient to furnish the necessary length of spillway in addition to the space required for the power house and in such cases it is particularly desirable to carry overflow or spillway passages through the portion of the dam occupied by the power house itself.

In the accompanying drawings illustrating specific embodiments of the invention Fig. 1 is a vertical sectional View of a turbine installation taken in a direction at right angles to the general direction of the dam.

Fig. 2 is a horizontal section of Fig. 1 on line 2, 2.

Fig. 8 is a horizontal section of Fig. 1 on line 3, 3.

Fig. 3 is a section on line a, a of Fig. 3.

Fig. 3 is a section on line b. b of Fig. 3.

Fig. 4 is a view similar to Fig. 1 illustrating a modified installation.

Fig. 5 is a horizontal sectional view on line 5, 5 of Fig. 4.

Fig. 6 is a vertical sectional elevation of a still further modification taken on line a b 0 of Fig. 7.

Fig. '7 is a section on line 7, 7 of Fig. 6.

1920. Serial No. 384,402.

Fig. 8 is a vertical sectional view of a further modification illustrating a different arrangement of the spillway passages.

Fig. 9 is a horizontal sectional view-on line 9,9ofFig.8. I 3

Fig. 10 is a horizontal sectional view on line 10, 10 of Fig. 8.

In the specific embodiment of the invention shown in Figs. 1, 2 and 3 a dam D has a crest C between the head water H and the tail water L and the head water face of the dam is extended backward by piers P between which are the flames or passages 13 to the turbines and the spillway. The head gates M sliding in ways M of the piers P and seating against the floor 15 of the intake control the flow to these passages 13 and auxiliary spillway gates S are provided above the dam crest C. The-flow from the head water H passes through passage 13 to the intake passage I and around to and through the turbine runner R and out through the draft tube F opening into the outlet passage 0 discharging into the tail water L below the tail water level. The runner R has its shaft extending upward through the crest of the dam and through the spillway passage A thereabove to drive the generator G on the power house floor or generator deck supported for instance by,

bridge or arch 21. Around the shaft 20 is the cylindrical pit T extending downward from the crest C and having a cover plate 22 at the crest level and a wall 23. The bottom of the pit Wall 23 is provided with a conical portion 2a resting on speed ring 25 supporting the. turbine head cover 28 and in turn supported upon the ledge surrounding the draft tube F. In the upper portion of the pit T braces 26 support a shaft bearing 27 and similarly the turbine head cover 28 in the bottom of the pit supports a shaft bearing 29 and also houses the operating means for the adjustable guide vanes 30 in the intake passage, these operating means comprising the control ring 31 connected to turn the stems of the guide vanes and moved by fluid pressure in cylinders 32 connected by piping to be controlled by a governor preferably on the power house floor above.

The walls of the pit T comprise the cast iron conical section 24 bolted to the speed ring 25 and provided at its top with the plate steel barrel 23 from this point up to just below the intermediate bearing 27 where a second cast iron section 23 is set in the concrete structure of the dam. A tube 35 extends upward from the pit cover plate 22 and around and protecting the shaft 20 from the flow in spillway A. This tube also provides a convenient passageway for access to the pit T so that the bearings and operating parts therein may be easily inspected and kept in adjustment and repair. lVhenever it should be necessary to remove the working parts of the turbine the cover plate 22 would be removed from above together with the tube 35 surrounding the shaft, the generator G having first been removed. In the embodiment shown in Fig. 1 this could be done by closing the spillway .gate S either with or without closing tae head gates M. IVhenever the local conditions should so require the spillway gate S could be arranged on the downstream side of the turbine pit T that is at or slightly beyond the downstream end of the crest C of the spillway A in which case it would be necessary to close the head gates M whenever any parts of the turbine are to be removed.

7 In the structure of this invention a spillway section A of the dam D is provided within the length of the power house and at the same time provision is made for removing the working parts of the turbine vertically into the power house so that these parts may be handled by the power house crane. hen the open air type of generator is adopted the turbine parts can be handled by the gantry crane which would be supplied to run the len th of the enerator deck. the same crane being used to handle both the generators and turbines. In regular operation and when the head water level overtops the spillway crest C the excess water will pass out through the spillway A over the cover plate 22 of the pit T.

The arrangement of this invention places the various parts of the turbine installation advantageously and compactly. The generator deck is above water level giving clear access to the generators at all heads and providing plenty. of surrounding space which would not be the case if the generators were sunken below the spillway level. Immetiately below the generators is the spillway passage A clear but for the single tube 35 extending upwardly through it. Below the spillway crest is the pit T surrounding the shaft 20 and providing easy access to all the turbine parts at the bottom of this pit where the turbine with its operating means is compactly assembled. The water inlet I to the turbine surrounds the pit wall 93 and utilizes the outer wall surface as its inner surface so that all the elements of the turbine fit compactly together. Similarly the draft tube F at its lower end is surrounded by the outflow passage 0 leading the discharge to the tail water L.

In Fig. 1 the turbine casing or intake 1 consists of thespiral inlet 4L5 through which were used, is avoided.

the water approaches the turbine axis in a spiral curve and then is gradually turned in a helical path at 46 so that it proceeds toward the turbine with a motion compounded of rotation about the turbine axis and a vertical downward motion. The top 47 of the intake I is formed to approximate a helicoidal surface or screw thread terminating after a rotation of 3,6 0 in an edge 48 just above the turbine proper. The lower surface 19 of the intake curves gradually from thehorizontal floor 15 of the gate chamber down to the edge 4-8, and by this design the sudden bend or elbow around which the water would have to flow in turning from the horizontal to the vertical direction, if no spiral guide walls It will be seen from Fi g. 1 that if the water should turn from the horizontal to the vertical in planes parallel to that of the figure without rotating about the turbine axis, this right angle bend would cause a loss of head and a disturbed condition of the water entering the turbine. The curvature would necessarily be in most cases'un duly abrupt, as shown by the small radius of the lower wall, marked 15, Fig. 1. By car rying the water in a. spiral, the curvature in the direction of flow is made much more gra dual. Moreover, if the water were allowed to enter the vertical portion of the conduit horizonta-lly, it would have to pass around both sides of a circular turbine pitand then turn into the downward direction, and there would almost inevitably be eddies and surging produced at the downstream side of the circular pit. The downward flowing water would subsequently be required to assume a rotation I either during its passage tarough the turoine speed ring or before reaching this point. If the water is turned, from horizontal to vertical without conducting it in a spiral course, the flow lines would be practically indetermi nate, and uncertain flow conditions would result. In the turbine casing of this invention the velocity can be closely calculated all points of the flow between the intake and the entrance to the turbine.

The useful water flow for the turbine after passing through the speed ring 25 and adj ustable guide vanes 30 enters between the blades of runner R and is discharged axially therefrom. In turbines of high specific speed such as would more usually be employed in such developments involving low heads, this axial outflow will also have a considerable whirling motion or rotation of the discharge stream a whole around the turbine axis. The discharge is received by the spreading draft tube F comprising anupper substantially straight portion of increasing cross section and a lower portion flaring outward therefrom and expanding radially with continuing increase. in cross section so that the flow is turned'symmetically and smoothly into the horizontal direction and has a large part of both its axial sure head at the entrance to the horizontal outflow O which continues to gradually increase in cross section to effect the final conversion of discharge velocity into pressure head at the tailwater L.

The outflow passage 0 surrounds the. discharge edge of the draft tube by a pair of oppositely directed half spiral passages and 61 forming collection chambers for the flow from the draft tube. These collection chambers 60, 61 extend upward as shown in dotted lines in Fig. 1 around the suspended conical draft tube walls 62 and 63 on each side, the discharge side of this draft tube wall being extended as a central pier 65 for providinga continuous foundation for the structure above.

The central pier 65 thus separates the flows from the collection chambers 60 and 61 as these flows pass into the discharge end of the outlet passage 0. It will be noted that the passages 60 and 61 he partly above the lower end of the draft tube, the material of the upper wall of the tube being formed as lips projecting laterally from the main portion of the walls 62 and 63. By locating the'outflow passages within the outer limits of the draft tube an economy of space is secured. The walls 62 and 63 as shown in Figs. 3 and 10 have a general elliptical form in section.

The draft tube of this invention thus has a vertically directed axial inlet F and a horizontal radially directed outlet 0 at an angle to each other and between these sections is the bend or elbow formed by the spreading passage. and collecting chambers described. The upstream walls of the collecting chambers 60, 61 form the end wall of the horizontal outlet portion of these collecting chambers 60, 61 and form relatively deep side portions which gradually decrease in depth in an upstream direction toward the upstream wall. Between these collecting chambers 60, 61 and disposed longitudinally of the outlet portion as shown in Fig. 3 the concrete formation projects downwardly from the roof of the outlet (see Figs. 3 and 3 and comprises towards the free end of the outlet the pier member 65 extending all the way down to the floor of the outlet. As shown in Fig. 3 this projecting portion extending downward from the roof of the outlet tapers gradually to become nar row toward the free end of the outlet.

The use of the spreading type of draft tube also offers important advantages when used with the arrangement of turbine here. described, since it would be objectionable to use the older type of draft tube involving an elbow or bent passage, since the elbow type of draft tube would discharge the water into the long horizontal discharge passage with too high a velocity in the. water and with too much disturbance. That is. the necessity of providing a long straight horizontal discharge passage to carry the water under the spillway section of the dam makes it desirable to use the spreading type of draft tube rather than the elbow type.

The helical formation of the intake passage I provides a supporting wall wrapping around the pit wall 28 and while in the specific embodiment shown in Fig. 1 this passage turns through substantially 360 it may turn through a greater or less angle and have a correspondingly smaller or larger pitch or be otherwise modified for instance as shown in Figs. 4, 5, 8, 9 and 10. To reduce the angle and increase the pitch reduces somewhat the amount of concrete and form work required in the construction but at a sacrifice of smoothness of curvature at the entrance to the casing. The choice of the angle would depend upon the economic relation between cost and efficiency in each particular installation.

In the arrangement shown in Figures 4 and 5, the design of the intake 1, and easing has been slightly modified by placing the edge 14:8 ninety degrees from its position in Figs. 1 and 2. The edge is here placed on the center line of the turbine in the direction of flow, that is, immediately in line with the center of the intake 1, so that the upper wall 147 of the casing is carried to less than a complete revolution. This reduces somewhat the amount of concrete and form work required in the construction, and while it gives shorter and not quite so gradual a curvature at the entrance to the casing, might be preferred in some installations.

In Figs. 6 and 7 a further modification is shown, having its intake passage in two halfspirals 70 and 71 developing in opposite directions from edge 54: of the crest G, the edge 78 here being placed in line with the center of the intake but on the downstream side of the turbine pit T. Thisarrangement is more economical in amount of concrete required, and in some instances would probably furnish as much guidance and as smooth lines of flow as it would pay to adopt. The curvature from horizontal to vertical at entrance is here more'abrupt than in Figures 1 to 5, but the formation of eddies behind the pit wall is prevented, and definite lines of flow are provided at all points. In this arrangement, however, the water will approach the en trance to the turbine proper without whirl, and this whirl will be introduced by the speed ring vanes 25 and 30. Fig. 7 shows in section the form of the tube 35 surrounding the shaft, which would be the same in the arrangements of Figs. 1 to 5.

Figs. 8, 9 and 10 show a still further embodiment of the invention in which the piers P supporting the generator floor are placed in line with the turbine axis instead of half way between the turbines as in Figs. 1 to 5. Spillways A between the piers are thus provided between the turbines and piers may be extended outward beyond the inclined face of the dam D on the discharge side to form the buttresses U. The spillway crest C has its'edge located at just in advance of the spillway gate S and below this crest the intake passage I leads downward and sidewise on inclined spiral lines to a helical portion surrounding the turbine pit T and tern'iinating in edge 18. It will be noted that this edge 48 is positioned differently from the edge 48 of Fig. 1, being terminated above the conical casing 24, and the upper end of the intake passage I is carried off at an angle to the passage 13 between the piers P.

In order to provide a continuous path for the'stresses developed in the dam down to the foundation the central pier in the discharge is made long and large in cross section and the walls 66 between the discharge passages of adjacent units are made narrower. The load from the central piers P carrying the generators and power house will thus be transmitted directly in a vertical plane to the foundation.

With the spillway passages thus located between the units the flow is not required to pass over the pit T of each unit. The pits T can thus be continued above the head water level as shown and the turbine parts can be removed at all times. The open top pit T is also advantageous in avoiding the use of the submerged cover plate 22 and also in avoiding all obstruction to the flow through the spillways A. The top surrounding wall T also directly supports the generator and in this construction a continuous tubular formation of the pit from top to bottom forms a rigid construction retaining the turbine parts in accurate alinement. It is obvious that in many instances of repairs the closing of the adjustable guide vanes or w'cketgates 30 will be all that is necessary and that the flow through the spillway may be maintained while repairs are going on. In all of the embodiments shown the structure provides for direct access to and removal and replacement of the turbine parts and atthe same time leaves large spillway spaces through the power house. The turbine parts are compactly assembled in the lower portion of the pit and the generally circular outline of the pit is maintained with the gate operating cylinders completely housed within it. The water passages for the flow through the turbines are also large in section and smoothly curved to efiiciently handle the flow and the combination of the turbine structure with the dam provides c011- tinuous supporting columns reaching from the generator deck to the foundation.

Each of the embodiments shown will have certain advantages in particular installations, for example, the arrangement of Fig ures 8, 9 and 10 is preferable to the others take passage for the flow to said runner, a

draft tube for the flow from said runner con'r prising a circular wall flaring at its lower end to turn the flow to the horizontal, and separate collection chambers for the flow from said draft tube extending upward and overhanging the edges of said draft tube wall.

2. In a hydraulic turbine installation the combination with a turbine runner, of anintake passage for the flow to said runner, a draft tube for the flow from said runner comprising a circular wall flaring at its lower end to turn the flow to the, horizontal, and separate collect-ion chambers on each side for the flow from said drafttube extending upwa "d and overhanging the edges of said draft tube wall.

3. In a hydraulic turbine installation the combination with a turbine runner, of an intake passage for the flow to said runner, a draft tube for the flow from said runner comprising a circular wall flaring at its lower end to turn the flow to the horizontal, and separate collection chambers on each side for the flow from said draft tube extendin upward and overhanging the edges of said draft tube wall and connected to the tail water by an outlet passage. I

it. In a hydraulic turbine installation the combination. with a turbine runner, of an intake passage for the flow to said runner, a draft tube for the flow from said runner comprising inner and outer circular walls forming an annular draft tube flaring outwardly toward the horizontal, and separate collection chambers for the flow from said draft tube extending upward and overhanging the edge of the outer wall of said drafttube.

5. In a hydraulic turbine installation the combination with a turbine runner, of a draft tube for the flow from said runner comprising a circular wall flaring outward at its lower end toward a horizontal direction and separate collection chambers surrounding said wall and overhanging the edges of said wall,

the upper surface of each of said chambers 3 increasing in elevation in passing around the draft tube wall to accommodate the flow.

(3. In a hydraulic turbine installation the combination with a turbine runner, of a draft tube for the flow from said runner comprising a circular wall flaring outward at its lower end into a substantially horizontal direction and a separate collection chamber on each side of said wall for the flow from said draft tube, said collection chambers being oppositely directed and extending around said wall and overhanging the edges of said wall, the floor of said collection chambers being substantially horizontal. v

7. In a hydraulic turbine installation the combination with a turbine runner, of a draft tube for the flow from said runner comprising a circular wall flaring into a substantially horizontal direction at its lower end, and a separate collection chamber on each side of said wall for the flow from said draft tube, said collection chambers overhanging the edges of the draft tube wall and being separated from each other by a central pier continuous with the draft tube wall on the downstream side thereof.

8. In a hydraulic turbine installation the combination with a turbine runner, of a draft tube for the flow from said runner comprising inner and outer circular walls forming an annular draft tube flaring outwardly toward the horizontal and separate collection chambers around said wall overhanging the edgev of the outer wall of said draft tube and separated from each other by a vertical wall downstream from the draft tube wall and forming a continuation thereof.

9. In a turbine a radially spreading draft tube discharging the flow outward away from the axis, and a collecting passage receiving the flow from the outlet end of said draft tube which projects into said collecting passage, the outer surface of said projection being formed so as to produce a laterally projecting lip whereby said collector passage extends radially inward around only a portion of said outlet, so that said collecting passage will have a portion lying nearer to the axis than the outlet of said draft tube.

10. In a turbine a radially spreading draft tube, discharging the flow outward away from the axis, and a collecting passage on each side receiving the flow from the outlet end of said draft tube which projects into said collecting passage, the outer surface of said projection being formed so as to provide laterally projecting lips whereby said collector passage extends radially .inward on each side of said outlet and only around a portion thereof, so that said collecting pa;- sages have portions lying nearer to the axis than the outlet of said draft tube.

11. In a turbine a radially spreading draft tube discharging the flow outward away from the axis, and a collecting passage receiviug the flow from the outlet end of said draft tube and having a portion extending radially inward around said outlet end and forming a laterally projecting and elongated lip, so that said collecting passage will have a portion lying nearer to the axis than the outlet of said draft tube, said collecting passage being adapted to receive the flow from said outlet at a considerable velocity and to cause said flow to be gradually decelerated.

12. In aturbine a radially spreading draft tube discharging the flow outward away from the axis, and a collecting passage adapted to receive the flow from said draft tube at a considerable velocity and to cause said flow to be gradually decelerated, said collooting passage having a portion extending radially inward around the outlet endof said draft tube and forming a laterally projecting and elongated lip, so that said collecting passage will have a portion lying nearer to the axis than the outlet of said draft tube.

13. In a turbine a radially spreading draft tube discharging the flow outward away from the axis and a collecting passage receiving the flow from the outlet of said draft tube, the outlet of said draft tube being partly formed as a depending projection extending into said collecting passage,-and a pier member extending in a downstream direction from said projection and forming a support for said projection from the wall below.

14. In a turbine aradially spreading draft tube-discharging the flow outward away from the axis and a collecting passage on each side receiving the flow from the outlet of said draft tube, the outlet of said d aft tube being partly formed as a depending projection extending into said collecting passages and a pier member extending in a downstream direction from said projection and forming a support for said projection from the wall below. i

15. In a turbine aradially spreading draft tube discharging the flow outward away from the axis, a collecting passage formed as a double spiral surrounding the outlet of said draft tube, the outlet end of said tube being partly formed by a projection extending from the wall of said collecting passage and having a generally elliptical form in section extending in a downstream direction, and a central tapered pier supporting said extension from the opposite wall.

16. In a'turbine a draft conduit comprising an axial discharge passage flaring outward at its end as a radially directed annular passage having itsdownstream portion extended further than the lateral side. portions so as to terminate in a non-circular opening discharging the flow into a surrounding discharge passage. 7

17 In a turbine a draft conduit comprising an axial discharge passage flaring outward at its end as a radially directed annular passage having its downstream portion extended further than the lateral side portions so as to terminate in a non-circular opening discharging the flow into a surrounding discharge passage and a discharge passage receiving the iiow from the outlet of said draft tube and having a portion extending radially inward around said outlet end and forming a laterally projecting lip so that said collecting passage will have a portion lying nearer to the axis than the outlet of said draft tube.

18. In a turbine a radially spreading draft tube discharging the flow outward away from the axis and having an elongated portion extending downstream, and a collecting chamber receiving the flow from the outlet end of said draft tube and having a portion extending upward around said outlet end and radially inward to form a lateral projecting lip so that said collecting chamber will occupy space above said outlet and lying nearer to the axis than said outlet.

19. In a turbine a straight draft tube having an outwardly flaring end spreading the flow laterally and an elongated downstream portion for conducting flow in a downstream direction and a collecting chamber receiving the flow from the outlet of said draft tube and extending radially inward from said outlet and forming a lateral projecting lip, so that said collecting chamber .will have a portion lying nearer to the axis than the outlet of said draft tube.

20. A draft tube for water turbines having inlet and outlet sections at an angle to each other, the outlet section having a flat floor surface and an upstream wall and relatively deep side portions of gradually decreasing depth toward the upstream wall saidside portions being entirely above the level of the floor surface of the outlet section.

21. A draft tube for water turbines having inlet and outlet sections at an angle to each other, the outlet section having a roof surface and a longitudinally disposed project ing roof portion with substantially vertical side surfaces extending downward from said roof surface.

22. A draft tube for water turbines having" extending downward from said roof surface.

24. A draft tube for water turbines having inlet and outlet sections at an angle to each other, the outlet sectionhaving between the sides thereof a projecting portion with substantially vertical side surfaces and being of gradually reduced thickness as it extends away from the axisof the inlet section.

25. A draft tube for water turbines having inlet and outlet sections at an angle to each other, the outlet section having relatively deep side portions and a relatively narrow middle portion formed by a longitudinally extending wall projection with substantially vertical side surfaces.

26. A drafttube for water turbines having a delivery section with an inlet formed by a. flared top wall port-ion the forward part of which is continued forwardly to form a longitudinal roof extension tapered away from the side walls of the section as the free end is approached and having substantially ver tical side surfaces.

27. A draft tube for water turbines having inlet and outlet sections at an angle to each other, the outletsections having relatively deep side portions and a relatively narrow middle portion formed by a longitudinally extending wall projection with substantially vertical side surfaces, the side portions curving inwardly as they approach the upstream end of the outlet section.

28. A draft tube for water-turbines having inlet and outlet sections at an angle to each other, the outlet section having relatively deep side portions and a relatively narrow middle portion formed by a longitudinally extending wall projection with sub stantially vertical side surfaces, the side portions having a varying depth.

29, A draft tube for water turbines having inlet and outlet sections at an angle to each other, the outlet section having relatively deep side portions and a relatively narrow middle portion formed by a longitudinally extending wall projection, the depth of the.

side portions gradually decreasing toward the upstream end of the outlet section and a central longitudinal pier member supporting said projection from the floor of said outlet section.

30. A draft tube for water turbines having inlet and outlet sections at an angle to each other, the outlet section having relativelydeep side portions and a relatively narrow middle portion formed by a longitudinally extending wall projection, the side portions curving inwardly and their depth gradually decreasing toward the upstream end of the outlet section and a central longitudinal pier member supporting said projection from the floor of said outlet section.

31. A draft tube for water turbines having inlet and outlet sections at an angle to each other, the outlet section having a flat floor surface, an upstream wall and relatively deep side portions of gradually decreasing depth toward the upstream wall both entirely above the level of said floor surface, said inlet-section having 'a bell shape lower end, and a cone projecting upwardly into said inlet section to form an annular passage with respect to said bell.

32. A draft tube for water turbines having inlet and outlet sections at an angle to each other, the outlet section having a flat floor surface, an upstream wall and relatively deep side portions of gradually decreasing depth toward the upstream wall, both of said side portions being disposed entirely above the level of said floor surface while said inlet section has a bell shape lower end, and a cone projecting upwardly into said inlet section 'for only part of the length thereof to form an annular passage with respect to said bell.

33. A draft tube for water turbines having inlet and outlet sections at an angle to each other, the outlet section having a flat floor surface and an upstream wall and relatively deep side portions of gradually decreasing depth toward the upstream wall, and entirely above the level of said floor surface while said inlet section has a bell shape lower end, and a cone projecting upwardly into said inlet section to form an annular passage with respect to said bell, said inlet section having a relatively long substantially straight conical section which merges with the bell portion.

34. A draft tube for water turbines having inlet and outlet sections at an angle to each other, the outlet section having between the sides thereof a projecting portion with substantially vertical side surfaces and being of gradually reduced thickness as it extends away from the axis of the inlet section, said inlet section having its lower end flared outwardly to form a bell, and a cone disposed centrally therein to form an annular passage leading to said outlet section.

35. A draft tube for water turbines having a delivery section with an inlet formed by a flared top wall portion the forward part of which is continued forwardly to form a longitudinal roof extension tapered away from the side walls of the section as the free end is approached, and having substantially vertical side surfaces, a central core disposed within at least a part of said inlet section.

36. A draft tube for water turbines having inlet and outlet sections at an angle to each other, the outlet section having a flat floor surface, an upstream wall and relatively deep side portions of gradually decreasing depth toward the upstream wall, both of said side portions being disposed entirely above the level of said floor surface while said upstream wall terminates substantially adjacent the lower end of said inlet section.

37. A draft tube for water turbines having inlet and outlet sections at an angle to each other, the outlet section having a fiat floor surface, an upstream wall and relatively deep side portions of gradually decreasing depth toward the upstream wall, both of said side portions being disposed entirely above the level of said floor surface and the lower end of said inlet section being flared outwardly to form a bell while said upstream wall terminates adjacent said bell in substantially a wedge shape formation.

38. A draft tube for water turbines having inlet and outlet sectionsat an angle to each other, the outlet section having a fiat floor surface, an upstream wall and relatively deep side port-ions of gradually decreasing depth toward the upstream wall, both of said side portions being disposed entirely above the level of said floor surface and the lower end of said inlet section being flared outwardly to form a bell while said upstream wall t erformed a spiral wall starting at the wedge and continuing outwardly in a downstream direction.

39. The combination in a draft tube comprising an inlet section of substantial length, a collector passage provided with a roof which in transverse sectionhas portions disposed at different elevations, said inlet sec tion having an outlet projecting below one of said roof portions and being turned downstream into said collector passage to form the other of said roof portions.

40. The combination in a draft tube comprising a relatively gradually flaring inlet section of substantial length, a collector passage provided with a roof which in transverse section has portions disposed at different elevations, said inlet section having an outlet projecting below one of said roof portions and being turned downstream into said collector passage to form the other of said roof portions, the roof portion at the center of said passage being at a lower elevation than portions of the roof laterally spaced from said central portion.

41. The combination in a draft tube, comprising an inlet section and horizontal dis charge passage provided with a roof which in transverse section has portions disposed at different elevations, said inlet section having a portion projecting below one of said roof portions and being turned and elongated downstream into said discharge passage.

42. The combination in a draft tube, comprising an inlet section and horizontal discharge passage provided with a roof which in transverse section has portions disposed at different elevations, said inlet section having a portion projecting below one of said roof portions and being turned and elongated downstream into said discharge passage,said downstream elongation being disposed centrally of said discharge passage whereby the discharge passage has two relatively deep side passages disposed substantially entirely above the floor of said discharge passage.

43, The combination set forth in claim 41 further characterized in that said downstream elongation tapers toward the downstream end thereof.

44:. A draft tube for Water turbines having inlet and outlet sections at an to each other, the outlet section having a iioor surface at least a portion of Which is substantially straight in a downstream direction, and

also having relatively deep side portions of gradually decreasing depth towards the upstream end of said outlet section said side portions being substantially entirely above the level of the floor surface of the outlet section, whereby there is provided a central elongated Wall portion extending in a downstream direction.

45. A draft tube for Water turbines having inlet and outlet sections at an angle to each other, the outlet section having a floor surface at least a portion of Which is substantially straight in a downstream direction, and also having relatively deep side portions of gradually decreasing depth towards the upstream end of said outlet section, said side port-ions being substantially entirely above the level of the floor surface of the outlet section, whereby there is provided a central elongated Wall portion extending in a doWnstream direction, and said elongation being tapered in transverse section as the free end' thereof is approached.

LEWIS FERRY MOODY.

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