US1848738A

US1848738A - moody

Info

Publication number: US1848738A
Authority: US
Publication date: 1932-03-08
Anticipated expiration: 1949-03-08

Description

March 8, 1932. L. F. MOODY HYDRAULIC TURBINE 2- Sheets-Sheet 1 Filed Nov INVENTOR 07/ f TOR EYS March 8,

L. F. MOODY HYDRAULIC TURBINE Filed Nov. 25, 1923 2 Sheets-Sheet 2 INVENTOR fit ' metric pressure. Troublefrom'this source speed types there is a tendencyunder some Patented Mar. ,8, 19 32 y 7 i UNITED STATESdPA TENT OFF ICE Q l i awman MOODY, or rnrniinnrvrmn, rmm'snvmn if i r 7 HYDRAULIC TURBINE i 7 Application filed Noveinb r 23, 1923. seal -No..676,479 1 7 a i This invention relates to rotary hydraulic ing an arrangement of control and check machines and particularly to hydraulic-turvalvesin the air supply and bines'and their draft tubes. a i Fig. 7 is a plan view of one of the operat- In some turbine installations and-under ing cylinders of the turbine showing a method someconditions of operation,particularly at for actuatingthe control valve of Fig. 6.. I5 gate openings less or greater thannormal or In the specific embodiment of the inven- "when the tailwatier'level is abnormally low, tion shown in the drawings the fiow entering trouble sometimes ;develops from unstable ,by intake 6 passes through the inflow guide flow in. thef clraft tube causing vibration of vanes 7 v and the runner, notlshown, and is 10 theturbine orfpo'w erhouse structure or 1111- discharged by the runner into the draft tube steady operation of the turbine. These con- Dhaving the outer wall-3 and the inner coni- (lltl'QllS may result from insuflicient margin foal core 9 both flaring outwardly to s pread of absolute pressure in the draft tube to mains and decelerate the flow inannular form and tain a continuonslb ody of liquid throughout discharging it through the outletlO into the sulting from the combinationjof height of) a t A p g 2m 6191 t bi above t 'flw t r l it h d f th isprovidecl to give access to the interiorof water discharged by therunner, and draft the draft tube D. V Y i tube efficiency, inconiparison withjthe baro- In turbines of high and moderate specific maysthus be due to a greater conversion "of conditions of operation, particularly at part" velocity'head into pressure head by the draft gate or when operating under heads below tube than theheight of the turbineabove'taih normal, for the discharge from the runner water permits. On the other hand,a draft to take place in an annular ring atgthe outer tubeof unfavorable form, such as anelbow :wall of the draft tube, leaving theisspace' the invention 50 P Fig. 6 is a sectional view of a detailshow- 'o'r vapor. This'tendency toward cavitation tube, may setup large eddies which: cause within occupied by water not advancing to-i "hydraulic impactlor shocks. i l ward the discharge. Under such partgate In either case, or whenever disturbances or reduced head operation the relative veoccur within a draft tube, I have found that locity. of discharge from the runner buckets ..the region particularly subject to the formais reduced to such an extent in comparison "tion of an objectionable void and to the setwiththe velocity of the runner vanes that the ting up of unstable conditions of How istliat discharged water contains large rotational L in and'around theaxis of the tube, and that components of velocity about the runner the tendency; towardvibration and disturbaxis. There is therefore a tendency to set ances maylbe overcome by admittingair tothe water in the central region of the draft the centralportion of the tubeljthis air being tube into rotation, andfor the tangential vefadmitted atf'a limited rate by properlyprolocity components to increase atpoints nearer portioning orfcontrolling the air passages; Y (the axis according to the law of the free In the accompanying drawings illustrating vortex, namely, that the tangentialvelocity a a i f varies inversely as gthe radius. Thisrelation Fig.1 isavertical sectional view ofatypicalv cannot exist throughout the space since it turbine installation embodying the invention. would call for an infinite velocity at the axis; Fig, 2 is a horizontal sectional view taken the tendency is however for the rotational vefo'n theline 2-2 of Fig. 1. a i a j V locity to become so high at points nearrthe I Fig 3 is an enlarged 'vertical sectional axis that the velocity head approaches the view of a ld etail." Q Pi i V limit set by the barometric pressure and the Figs .4 and 5 are cross sectional views of elevation above tailwater, and the flow then different forms of pipe admitting air into endeavorslto separate and .to form a vortex the draft tube. 1 1 leaving a void a'roundthe axis 'filledwith air the tubeQthat is, an excessive draft head recollecting and discharge'chamber llileading a v i is likely to cause unstable operation or vibration. When there is such a tendency toward cavitation, it is useful to supply air to the central space to avoid instability, shocks or vibration troubles.

In draft tubes of elbow types trouble is likely to occur from the formation of eddies due to the rotational velocitiesg-and in tubes of symmetrical type such as the spreading tube shown in the figures the ability ofthe tube to convert the velocity [head of rotation into pressure head may in some instances cause excessive vacuum in the drafttube at part gate, since the absolute velocity of dis charge from the runner may be greater at 7 part gate than at normal gate. In either case it 'is frequentlyusefulto admit air to the tube and thus to avoid the effects of cavita tion-or to cushionthe impacts or shocks due to-turbulence. VVhen air ismerely admitted to the outer flowlines through the outer wall of thedraft tube, there is aitendenoy for the flow in the outer.portionofthe tube to carry the airaway before it can penetrate to the jcentra-l'portion so that the desired relief'is :not secured. Moreover, the-centrifugal force of the whirling water in the draft tube causes 'an increase.of"absolutelpressure at the'outer' wall' which opposes the flow of air into the "tube at this point. 'I have foundthatthe' supplying ofa suitable amount of air to the inner portion of the tube will overcome any objectionable tendency toward shocks and vibration without interfering with the outer efiiciency of the turbine. t I, I

I, therefore, provide a pipe or 'hollow'vaneflow lines orimpairing .the'power output or shaped extension 15 'havingits end '16 appreaching inward from the outer wall 8 of the drafttube and opening into the inner or substantially central portion of the draft tube as shown 'for instance in thedrawings.

'By thismeans,'the air is carried through the "rapidly-moving annular'body of water and 'adniitted'into the inner portion ofthe tube.

Ava'lve 17 is provided for the pipe 15to control the ra'teofflow of the air. Acheckvalve may also be'provided'in the air pipe so'that it will close during any'condition tending to set up a back flow and will thus prevent the discharge of water from the draft tube. For instance, as "shown in Fig. 6 pipe 15 maybe provided with a checlrvalve 21'and a control valve. 17 This check valve'will close during anyconditiontendin g to set up a back flow and willthus preventthe' discharge of water from the draft tube. When the pressure withinpipe l5 is less than that oftheatmos- 'phere, the check valve will open and permit shown, or othersuitable means.

just described, the valve is "provided with mechanical hand control consisting of a hand wheelQtcarryingthe SlGGVQgQK) engaging the backed off tot-he end of the stem allowing the sleeve '25' to slide :freely through the yoke 27. -At 28 is shown a mufilerflor silencer through which air is; admitted to thec'ontrol valve and comprises an outer casingand a tapered inner casingtherein, thereby forming innenand outer converging passages. This mu'fflernlay consist of a series of bafiies; and a slotted cylindrical diaphragm, as

' Fig. 7 shows in plan view one of theturbine operating cylinders 29'-'formovi ng the turbine gates'through thefrod 30. .On this- ,lOd is fittedan arm 31 carryiiigiacanr'32. At any desired position of the gates, the cam may be adjusted to actuate alever 33 attached to the stem ofa two-way cock 34. When this cock is opened, pressure fluid is admitted to pipe' 20 which is connectedv by suitable piping with the pipe :20 of Fig. 6. Insteadof spring 23fluid pressure "can, if desired, be admitted to the interior of the plunger forclosing the valve 17. Instead of'the fluid operated 'valve 17 a valve operated byeleotric motor or mechanically operated valve can be used wheremore convenient. Instead of being actuated by the turbine gates, the fluid threaded stem 26. When the valve is desired .toloe under fluid control, the hand wheel 24 is or electric or other means. can be controlled by hand from the switchboard or other suitable point or the valve may be automatically actuated by the pressure within the. draft tube.

, 'When vibration within the draft tends to. develop at some partial gate opening-of the turbine, the fluid or electrically operated valve, such asflT, may be arranged to be automatically actuated by the turbine gate mechanism in a manner similar to that .shown,"so"" ient'source of fluid pressure, such as water that air will be admitted to the draft tube from the penstock or from the governorsystem or air from the, accumulator tanks, may

beused. y 'i 'The pipe 15 may draw its supply of air from any suitable source such as the passage 12, or if desired, its inlet maybe placed outside the buildingor in a separate chamber l arr'angedto shut ofl" from the powerhouseiany noise created by the suction of. air into the cend fi e i i Th e t a deit P es lie will preferably be provided with silencer I or muffler, such for examplel asithe;periphertally-slotted: cylinder 38 shownin the.draw' ings,*in order tojavoid the hissing or whistllng. of the enter ng air. 1

The end of the pipedischarging the airi j into'the draft tube may be "formedin any desired manner to increase the suction or aspiration efi'ect.

instance the end 16 of the pipeloinstead of.

As shown in Fig. 3 for beingtangential maybe bevel-ledor inclined 1 so as to extend. diagonallyacross the flow which usually has rotational or'whirlingcoinlponents inwa horizontal plane around the: axis 7 15 3 diagonal inclination of the edge of the end as indicated the arrow (Fig. T2). This gorifice will increasethe suction? effect. As

* shown inFigsl and 3 the'direct ion of the ybevellingof the end :16 of the pipe in. addi ponents ofthe flow; H i

The pipe 15 maybe extended into the draft tube any desireddistance or itmay be made adjustable to have this distance varied. The

' pipe may be circular in cross section as shown in Fig. 4 or generally oval or vane shaped in section asshown at 15- in Fig. This latter form will give a narrower pipe with less resistance to *the flow durmgnormal opera n n when its longer axis is arranged'approximatelyto coincide with the n'ormallines of t flow of the water inthedraft tube.

. With this air inlet extending inward; to

point within theou'ter wall of thedraft tube *the air is carried through the swiftly moving stream 'ofwatera't the outside and is intro .duced into the central region of .the' tube which is filled with water not partaking of the general flow. In this central space the;

water is, of-; courseyqsubjectj to turbulence and local reversal 'offlow with atendency at times to the formationof-a -Void near'the axis, that is, a cavitywhere airio-r vapormayfcollect. The use of the air inlet of'thls lnvention is effective in? eliminatingithe tendency toward shocks andyvibration without affectingth e efficiencyof theturbine; or its power output. As a means-ofantroduclng air into thejbody offlowing fluid in a conduit for the purpose of filling'; Voids or cushioning hydraulic shocks, the air inlet means here described may also be'applied particularly certrifuga-l' pumps.

" -Iclaim: i

1.1In a rotary hydraulic niachinethe com bination with arunner and a water conduit containing water flowing with rotational velocity componentsaboutthe axis of the conduit, of an air inlet extending withinthe flowin said condu-itand adapted to pass air into =:air intowthe interior of the body of wate therein;

to other hydraulic machines,

the interiorofthe body .of water therein. 1 r 2.; In tairotairy hydraulic machine the combination with a waterIconduitcontaining a runner, of an airinlet-extending Within the flow in said conduit and adapted to pass 3-1111 a rotary runner, of an air inlet extending inward from 7 0. hydraulic machine the comi bination withragwater conduit containing a :a sideitoward the central portion of said con- .duit and adapted to ipass air into said 'por-1E75 i 4. In a hydraulic turbinetthe combination of i-a :draft tube and an air inlet'passing througlra portion of the water stream Within said draft tube and opening at an-intermedi ate point within the body of Water in said draft tube. i i

531a a hydraulic turbinethe combination 'Wltll' a water conduit contaimng a runner, of a an: air inlet extending inward fromthe outer Walltoward the central "portion of said con-. duit and adaptedtoipass air into said portion. 6. In a hydraulicrturbine the-combination -=with a water conduit containingarunner,of an air. inlet extending inward :from'the outer wall to apoint lntermedlate between the center and the outer wall of said conduit and adapted topass air into said, conduit.'

7. .111 adydraulic turbine the combination with a water conduit containingaqrunner,of? an: air inlet extending throughthe flowto a .pointwintermediate between the center "and theouterwall'ofsaid conduit and'adapted to pass aininto said conduit. Y 1

8. Ina hydraulic-turbine thecmnbination of a draft tube and an air inletpassing through a portion of thewater stream within said draft'tube and opening at an intermedi ate pointwithin thebody of water in said draft tube, said inlet terminating an end ebliquely inclined to theflow; y

'9. In -a hydraulic turbine the combination with a Water conduit containing a runner,

of ana-ir inlet extending within the central portion of said conduit and-adapted togpass air into said portion and means for autono I matically admittingair through said inlet uponoccurrence-of predetermined: conditions in said conduit.

' v 10. In a hydraulic turbine the combination Witha water conduit containingarunner, of a stationary air 1111611 extending within the flow in said conduit, and adapted to pass air into the'interior'ofthe body of water therein,

nd adjustable means for controllingthe rate of flow ofair into said conduit.

'11. In ahydraulic turb'ine'the combination with a water conduitcontaining a runner, of

a stationary air inlet extending within the flowin said conduit and adapted to pass air into the interior- 0f the body of watertherein, and means for opening or closing said inlet to the admission of air, said-means being controlled by, the position of the turbine gates.

. In hydraulieturbine thejcombination with a water conduit containing a runner, of a stationary air inletextendingw thin the 4 flow in said conduit and adapted to pass air into the interior of the body of water therein, and remotely controlled valve means for opening or closing the admission of air to said inlet, said means being operated from any convenient point.

13. In a hydraulic turbine thecombination with a water conduit containing a runner, of an air inlet extending within said conduit and adapted to pass airinto the interior of the body ofwater therein, said inlet passage being equipped with means for decreasing the sound of the entering air comprising a cham ber providing an enlarged compartment at r the entrance end of said inlet.

- 14.1111 a hydraulic turbine-the combination with a water conduit containing. a runnor, of an'air inlet extending inward toward the central portion of said conduit and adapted to pass air into said portion and means .,forautomatically,admitting air through said inlet upon occurrence of predetermined pressure conditions in said conduit, and sound zdecrleasing means at the entrance to said in- ;let. 3

wwitha runner and a draft tubere'ceiving the .flow from said runner, of an air inletextend- 15. Ina'hydraulic turbine the combination with a'water. conduit containing a runner, of

an air inlet extending within said conduitand \adaptedito pass air into the interior of the body ofwatertherein, and means for 1 automatically closing said inletupon the ocmatically admitting air through said inlet upon occurrence of predetermined pressure conditions in said conduit and automatically 1 closing said 'inlettolprevent. reverse flow therein.

17. In a hydraulic turbine thecombination with a runner and a draft tube receiving the flow from said runner, of an air inlet extending inward from the outer wall toward the central portion of said draft tube and adapted topass air into said portion. p

Q 18 In a hydraulicturbine the combination with a runner and a draft tube receiving the flow from said-runner, of an air inlet extending inward to a point intermediate between the axis and the outer .wall of said draft tube and adapted to pass air into said portion.

-19. Ina hydraulic turbine the combination ing within the central portion of. said draft tube and adapted to pass a r into said portion and, meansfor automatically admitting a r that of the air outside.

upon'occurrence of in said draft tube. i I 20. In ahydraulic turbine the combination with a runner and a draft tube receiving the predetermined conditions flow from said runner, of an air inlet extending inward through the flow toward the central portion of said draft tube and adapted to pass airinto said portion, said draft tube having a central core with an annular passage around it.-

21. In a hydraulic'turbine the combination,

of a draft tube :anclfan air inlet passing through'a portion of the water stream within said draft tube and opening at an intermedi- I ate point within the body of water in said draft tube, said inlet comprising a hollow vane-shapedmeinber'positioned to give small resistance to the flow. t

22. .In a hydraulic turbine the combination with a water conduit containing a runner, of

an air'inlet extending inward toward the central portion of said conduit and adapted to pass airinto said portion and means for automatically admitting air through said-inlet upon occurrence of predetermined conditions in said conduit comprising spring controlled check valve means.

23 In a hydraulic turbine the combination with a water conduit containing a runner, of

an air inlet extending within the central portion of said conduit and adapted to pass air into said portion: and means for automatically admitting air throughsaid inletupon occurrence'of any desired degree of pressure differconduit and ence between the pressure in said 24. In ahydra-ulic turbine the combination with a water conduit containing a run1ier,'of

a stationary air inlet admitting air to the 7 central portionlof the conduit and adapted to pass air into the body of water therein, said inlet passage beingequipped with means for decreasingthe sound of the entering air.

25. In a liydraulicturbine the combination. with a water conduit containing ar unner, of ,a stationary air inlet admitting air to the central portion of the conduit I V I and adapted to pass air into the .body of water therein" said inlet passage being equipped with means for decreasing the sound of the entering air and comprising ,aplurality of openings.

26. In a hydraulic turbine the combination with a water conduit containing avrunner, of

- a stationary passage having at least a portion thereof converging to-form an air inlet ad mitting air tothe central portion ofthe conduit and adapted to pass air into the body'of water .ther'eimsaid inlet passage li'avingfa plunger valve therein for through said inlet. 1 p

.27; Ina hydraulic turbin'ethe' combination with. a water conduit containing a- 'runner,of

admittingair a stationary air inlet passage admitting air to, the central portion of the conduit and adapted -to'pass air into the-body of water therein, said inlet passage being equipped" with converging means for decreasing the "sound'of theentermg a1r, and a plunger valve passage for admitting air central portion of the conduit and adapted to pass air into the bodyof water therein,

' said inlet passage being equipped with means for decreasing the sound of t e entering air comprising a plurality of restricted openings.

29. In a hydraulic turbine the combination with ai-water conduit containing a runner,

of a stationary air inlet admitting air to the central portion of the conduit and adapted to pass'air into/the, bodyof Water therein,

said inlet passage being equipped with means forimposi'ng a resistance to the flow of air therethrough in order to provide low velocities and consequent avoidance of the creation of sound waves.

30. In a hydraulic turbinethe combination witha water conduit containing a runner, of

a stationary airinlet admitting-air tothe central portion of the conduit and adapted to pass air-into the body of water therein, said inlet'passage .being equipped with means for so imposing a resistance to the flow of air therethrough in order to provide low velocit es and consequent avoidance of the creation of i sound waves comprisinga plurality of tortuous passages for the air flow.

31. Ina hydraulic turbinethe combination with a water conduit containing a runner, of a stationary air inlet admitting air to the central portion of the conduit and adapted to pass air into the body of water therein, said inlet passage having an, opening in contact with the moving water in the turbine so formed as to make the velocity head of said water eiiective in reducing the pressure at said opening below the static pressure in the water and permiti ting drawing air into the turbine when the.

water pressure is above that of-the atmos-. phere. i

32. In a hydraulic turbine the combination" with a water conduit containing a runner, of

an air inlet extending inward toward the central portion of said conduit .and adapted to pass air into said portion, and plunger valve means for automatically admitting air through said inlet upon occurrence of predetermined conditions in said conduit and independently of the turbine speed.

33. In a hydraulicturbine, the combination comprising a water conduit containing a runner, an airinlet adapted to pass air into said conduit below said runner, and means for admitting air through said inlet automatically only upon occurrence of a predetermined part'gate operation.

- 34. In a hydraulic turbine, the combination comprising a water conduit containing a runcentric converging passages.

means admitting air through said; inlet auto maticallyupon occurrence of a predetermined position of said-servo-motor, said automatic 1 means including a valve "and acam movable with said servo-motor adaptedto eii'ect actua l tion of sa-id'valve when reaching a predetermined position in the servo-motor movement.

In a hydraulic turbine, the combination comprising awater conduit containing arun ner, a passage for admitting air tos id eon duit, and ani'nlet iorjsaid passageequipped with means for decreasing the sound of the enteringair comprising a plurality of con verging passages.

36. In a hydraulic turbine, the combination comprising a water conduit containing a runner, a passage for admitting air to said conduit, and an inlet for said passage equipped with means for decreasing the sound of the entering, air comprising a plurality of converging passages disposed in opposite directionsand communicating with each other.

37. In a hydraulic turbine, the combination comprising a Water conduit containing a runner, a passage for admitting air to said conduit, and an inlet for'said passage equipped with means for decreasingthe sound of the entering air comprising a plurality of con 38. I11 a hydraulic turbine, the combination comprising a water conduit containing a runner, an airinlet adapted to pass air into said conduit, and means for admitting air through said inlet automatically only. upon occurrence of a predetermined part gate operation, said means including a power jactuated remote control valve mechanism operated in accordance with the part gate operations.

39. In a hydraulic turbine, tion comprising a water conduit containing a runner, an air inlet adapted to pass air into said conduit, and means for admitting a air through said inlet automatically only the combinaupon occurrence of a predetermined part gate operation, said means including a pres- I sure fiuidoperated valve and control means therefor. 40.111 a hydraulic turbine, the combination comprising a water conduit containing a runner, an'air inlet adapted topass air into said conduit, and means for admitting. air through said inlet automatically only. upon occurrence of a predetermined part gate operation, said means including a spring operated valve for said inlet.

41. In a hydraulic turbine, the combination comprising a Water conduit containing a runner, an air inlet adapted to pass air into said conduit, and means for admitting air through said inlet automatically only upon occurrence of a predetermined part g e. peration, l id m ns i c di g a. spring operaited ivalve 01 saidfinljet and power means for operating theValve. against theaction of said spring. 1, V v

In e hydraulic turbine; the combinationvcomprising a: water conduit containing a -r unner,'an air inlet adapted to pass air into said conduit, and means for admittin air through said inlet autom'etioally only upon oceurrenee of a predetermined part gate operation, said means including a. valve fonsaid inlet and means for opereti'n the same in one direction by pressurefluiif and in the other direction by a s rin LEWIS FERRY .MOOiJY.

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