Water Turbine-1 - Copy

8/18/2019 Water Turbine-1 - Copy

1/10

8.

WATBR WHEELS3. They are not suitable for high water heads.4. Their speed can not be easifi regulated.

Advantages of water turbines :1. They have long life.2. They are efficient and can be easily controlted.3. They have-outstanding ability to "oi". standby units.4. They can be made automatic cootroil.O.5. They can work under

any head.Do you Know

What-is.water wheel'? Explain the various forms of waterwheels.Describe with heat sketches.(a) Overshot water wheel,(D) Breast water wheel,(c) Undershot water wheel, and(d) Poncelet water wheel.Distinguish clearly between j(a) Overshot water and undershot water uAeel.(b) Undershot water wheel und pon"eiei

*u,", wheel.Give the advantges and disadvantages of water wheel.Give the advantages of water turbines.Name the classification of water turbines.

-1-

2lf2. IMPULSE TURBI NES

3.

4.{6.

I. Introductlon. 2. peltonwheel.3. Nozzle.4. Runner and buckets.s, latue. 6. Brakins jet. _7. irri ;;;,'ii o, rmpatreturbine.8. Powerproduced by an tmltulse turbine. i.--i6ii"n"iq of an impulseturbine. 10. Eydraulic efficiency.II. Mrrh"ri;;i"'"nrir*r. 12. Over_alleficiency. Ij. Nuiber of jets for a peltoiwheel. 14- Sizeofuckets of a pelton pheel. IS. Nunier of b*i"t, on the periphery of Peltonwheel. 16. Design of pelron inrrir.--iz. Governingof animpukc turbine (pelton wheel).

21.1. IntroductionIn an impulse turbine, the entire available energy of the waters first converted into Jlnliic ;;#;-bt;assing it throush nozzres ;hich are kept close to the- runi6i- th'e *"t"r-.nters ihe ,uooingheel in the iorm of a iet, which' _pi"gtl on the buckets, fixed tohe outer periphery of ihe' *h;;1. '..r' 5wn uu ]utr oucKets' IHe(The jet of water

impinges on the buckets with a high velocity,,T9:lt:l flowing over thc' uu"*r,-L"iJr"i",ro a row velocity : thusmpartrng energy to rhe runner. The pressui"';i ;;;;;:rUlii,",ntering and leavins ,rhr. u.u.rrrr,. ir_ ui.Jsp-n.r,c. The commouest

;:i.T'" of an impuisive turbinc'ir- p"r"ti'o'Lneer, which is discussed2l'2. Pelton wheel

The *pelton wheer is an impursive turbine used for high heads

ffi*,i".*::s**;fu('iii;l*il,:l.Jiiff."*$islfitf

i''ft


2/10

,g2

of water.

IMPULSB TURBINES

It has the following main components.

IMPULSE TURBINES ftInumber of buckets are fixed uniformly. A. bucket resembles lo ahemispherical cup or bowl with a dividing wall (known as splitter)in its centre in the radial direction of the runner as shown inFig.2l'2.l

Fie. 2t.l2l'3; Nozzle

-It is.a circular guide mechanism, which guirles the water to

Py "t a designed direction, and also to regurite the flow of water.tnrs-water, rn thc form of a jet, strikes the buckets. A conicalneedle or spear operates inside the nozzle in an-axial -oiti.iion.rjt: ryain purpose..of this spear, is to control or regulate the


3/10

u IMPULSB TURBINESagainst accident and also torrevent the splashing of water and leadthe water to the tail race. rn" ciring-is ieneralty made of cast orfabricated parts.2,.5. Braking jet

Whenever the turbin-e has to be brought to rest, the nozzleis completely closed. It. has, Ueen observedl that tf,i-iuno.iio.,on revotving for a considerable time, dui to loritiu, U.r"rl"iti"t",to rest. In order to bring the runner to tist in a- srrbiiiirir","

,l""ilnozzle is p-rovided in s'f[ " y"y, th;t it windirecil-i*-ti*ut.,on the back of the buckets. tt t"t. ; ; 6;;k;-io, ,'"aiuJiog'tt"speed of the runner... .T " jet of water, issuing from the nozzle,strikes the bucket atits splitter. The spritter then-spriii up ttrl"t i" l";;;ft. "6-*-o"r,of the jet grides. over *re iniro -'iu.ri." ? oni p";ii*";fil"-u'uo"and leaves it at its extreme-edge. fne-otfier part of the iet elidesover the inside surface of.the -ottei poitl"i- .ii-inJ

"ui"-u'o-o'[u"",t at its extreme edge as shown in Fig:ti:3-.'

Flg. 21.3

A littre consideration 'will -show, that the mid-point of thebucket, wheie the jet strikes tn" s-prittir lrni gets divided, forms theinlet tip, and the iwo extrem" a it, *T"* the divided jet leavesthe bucket, form the two outlet tiprl--'2,'7. Work

done by arr imputse turbineFirst of all. draw the inlet and outlet -velocity triangte at thesplitter (which wilr be a.s.traight ilo. ""i9 "" o any one of the ourertips of the hemispherical bucfiei;, ;h;;'iii rig. it.d.-Let Z:Absolutb velocity of the entering water,

Zr:Relative velocity of water to bucket at inlet,y1:yelocity of flow at inlet,Yr Yt Zrr=Corresponding values at outlet'i.e., of the waterar tne potnt of leaving,

D:Diameter of the wheel,d:Diameter of the nozzle,JV-Revolutions of the wheel in r.p.m.

IMPULSE TURBINES

u:Tangential velocity of buckets,(Also known as peripheral velocity of wheel)

Fie. 2l'4

f :Angle of the blade tip at outlet,H:Total head of water, under which the wheel is

working.Since the inlct triangle is a straight line, therefore velocity of

whirl at inlet,Vr:V and Vr-Y--u

Since the Pelton wheel has an axial flow, thereforeu-t/.r Or V1:Yr-l/-s

From the outlet triangle, we find that velocity of whirl atoutlet,

Ya,:Vt as $-u:(V-o) cos $*uwe know *":t

i::Tjili,ffiTl'io,n,(v,-K,,)I

: V(V,*V,)In this case, V,,, is negative because V6 is in the oppositedirection as that of V.,

work done t':::::H6o"" : L 7Y.o I v,,u;yo6

:4*I* ...(... u1_0)cc: ry*% ...(.: vn:v,1coso-o)

l):-0

9\./

lY,j[(V-v) cos f -u]] (... v11*t/,-tt_1,


4/10


5/10

IMPULSE TURBINBS

ilitIIt

ifI

i'I

-.-_, Example 21.1. A pelron wheel deveiilf:J:; ii,:f";tit::;r,:i";;;';ft :;::::,f ;;,',x ,. F#r:"If;;hediamekr;j,ii-iiZ'iii;;;,*:::"ff"f,:;,":i"{:,,:,(Gauhati

v.e Io c i ty fo r *i"noi"i"rhati University, I97J)Solution.$ven. Power, p:4,500Head of water, f/:100 mOverall efficiency, rlo: g5% :0.g5uoetflcient

of velocity,

IMPULSE TURBINES

Speed of wheel, /V-600 r.p.m.Discharge, g-50litres/sec:0.05 mr/secDia. of whcel, D:60 cm-0.6 mCocfrcient of velocity,

Cr:0'98Horse power avaitabte at the noz1le

Let p:power availablcat the nozzle.Using the relation,

P: ttt++ with usual notations.- l'ooox9jo5x l4o -93.3 H.p. Ar*

Hydraulic eficiency of the wheelLet h:Hydraulic efrciency of the wheel.We know that the vclocity of jet,

Y :9,

nf 2c H: o. s sy'zfg:gTi-i6d- m/secwe arso know that ;::;'rtf,ifflcrocity orthe whecr,

,: "Dr{- zxo'ox6o0:rgtri./r*Now using thc relation,

ou (

,^: 2tt(v-olL*eos 6) with usual notations.:,#l+cos189")'-0.929

Example 21.3 (S.I..ln\\. -A felton wheel, worklng uder a headf 500 metris, prodices.r3,00ii iW ;;'7i;'r.p. . . rf the eficiencyf thewheettsbsol", dltgrmiytol iirriiisl of tle turbtnc,lD ao-letu.

of tne wheet, and (c) diaieiei ;i-|fr; ytzzte-. Assume iittattcSofudon. . (Ranchi Untversityr lgTt)Givcn. trIead of water,

cr: ILet d:diameter of the noz,zle.We know that the velocity of jet,

lo: with usual notations.

Solution. (Delhi Anners{ry, igi))

n : gr riu: I x y'2I_9T_iFlTO n/sec:44.3 m/secUsing the relation,

Piok-f5_-o.8s:_4,500. 27i,om;c-"tri-

ftO: T#Bj :3.975ms/secdi."h,ils".*rf*, T1l:TlTffi$j3"wheer shourd be equar to the

Q:ttx f,xdo3.97s:44.3xI xdz

": { ?a3t;:o'339 m:33'9 cm Ans.,r,y,f 1X#:]i;, urir';{;,;::;,;o;,,iy^:?:,i,:,:r::bucketsandischarge throuph tni ,iti,ii ;l"ii'ii,:-^i",-^' n s ..at 600 r.p m. Theis 60 cm. Find

,tozzle is 50 litres/sec and_diamerer

o1. tii rn"etQ) *e horse power available at the nozzle,(b) hydrautic fficiency of wheet, ij ,"ig9tgr1-of-velocity is 0.98.

Given. Because of --- .*ni"n tn#,TTitT"o".'ilrlSckets' the an gle through

C: lg0,Head of water, If: l4O m

Power,Spccd,Efficiency,

Dlscharge of the turbineLctUsing tho relation,

rI[:5(X) mP:13,000 twN*429tlo:t5o/-0'85

p=Discharge of tbc turbino.

Ptlo:F1flp-g- with usual notations.II


6/10

6ilIMPULSE TURBINES

(a) dhmotcr of the jet,(6) width of thc buckerr,(c) depth of bucketr,(d) numbor ofbuckcts.

rA* 65 "^ r t#'H'r{.tW'inHightights

X;"r)_#j:l':;it-::$l:F: arc foundby dividing theah No. or tcrs. rn a pelton wheel, are found bytotat discharge oi t n6 t urulni 6i&"'er=;d" ri""l""i"-:ii.. Size ofthe buckets

.where

6.

where

'__,__1., D9sc.ri.be, with rhe hefp ofan tmpulse turbine.. -4. Derive an equation for thewheel.

simple sketches, the working ofhydraulic eftciency of a pelton

*ooili #.litrlJ:, turbine. is that in which the water enrers theon the outer periph"d:?;:*h3"1f inninees 'on the ui"tJtt,-'hteo

Hydraulic efficiency of an impulse turbine.,o:2v(Y-o)(l+cos ,)---vj-u_ Tangential v-clocity of buckets,Z:Absolute velocity Lf tl" jet, anaC:Angle of the blade tip at oudet.3. Horse power produced by an impulsive turbine.

_ York done/kg of water x Weight of water . -e -- " in kg flowinq/see

REACTION TURBINES

l. Introductlon. 2. Maincomponentt ofa rgactba turbine. 3. Pens'tock. 1. Spiral caslng. 5. GuI& meclsnism 6. Turblae rumer.7. DWr'cnce betwccn an impulse turblne and a reaction turblne. 8. Clatsificationof rcrctlon turblnes. 9. Radial flow turblnes. 10. Axtal flow turbines.11. Mtxcd flow turhines. 12. Inward flow rcactton turblnes. L3.Work doncby an lnwardflow rcactlon turbine. 14. Ourwardflow rcactlon turbines.15. Disclnrge of a reaction turblne. ltf. Powcr produced by 4 rcactiontarbhc. 17. Eftctencles ofa reaction turbine, 18. Ilydrasltc efrclency.19. Meclunical eftciency. N. Overall eficiency. 21. Frarcis' turbinc.22. Kaplan turbhe. 23. Draft tubc. 24. Typcs of draft tttes. 25,Contal drafttubcs. 26. Elbow draft tube* 27. Eftciencyofa*aft,tbc. 2t. Cavltctlon.

tI,. IntroductionIn a reaction turbine, the watcr enters the wheel under pressurc

and flows ovcr thc vanes. As thc watef, flowing over the vanes, itunder pressurc, therefore the wheel of the turbinc runs full and maybe submerged below thc tail racc or may discharge into thc atmos-pherc. Tf,e pressure hcad of water, whilc flowing over the vanes, i3

converted inlo velocity head, and is finally rcduced to the atmos.pheric pr6sure, before lcaving the wheel.2il:2. Mein components of e reaction turbine

A rcaction turbine has the following main components.lil'3. Penctock

It is a waterway providcd to carry the watcr from thc rcscrvoirto thc turbine casing.- At the inlet of a penstock, screehs (calledtrashracks) arc provided in order to obstruct the debris fromcntcring id'to it. The pcnstocks are gencrally manufacturcd at thceitc and arc thoroughly tested for:

(a) tcakproof, and (b) Eafc working@5

222.

wherc

(c) Width:Sxd(D) Depth:l.2xdd:Diameter of the jet.

No. of buckets: finrtD_Diameter of the runner whcel,d:Diameter of the jet.

Do you Know ?l. IVhat is meant by an impulse turbine ?

action2iu:Jff:.thediffergnce between an inpulse turbinc and a re-

5' Show from first principres that _the theorcticar varue foreripheral coefficient ora peiion-dnir iit.l.of p"tfoo gf;J*l factors does.the number ofjets dcpend in the ca,seucteli ,"Yf:i# J|;f;:l"ftwidth orthe buckets and dcpth orthe

E. By means :l i_:"t ,ketch,-giving .complete operation,xplain how the turbines ar€ gov€rned';r

constant speed operation.


7/10

526 REACTION TURBINES

upto 30mup to 100 m

more than 100 m

Fls. 22.1

reaction turbine consists of runner bladesrings, depending upon thc type of turbine.

The blades are properly designed, in order to allow the water to cnterand leave the runner without shock.

The runner is keyed to a shaft, which may be vertical or hori-zontal. If the shaft is vertical, it is called a vertical turbine. Simi-larly, if the shaft is horizontal, it is called a horizontal turbine.22.7. Difrerang:-betwcen an impulse turbine and a reaction

turbine **Following are the few points of difference between a reaction

turbine and an impulse turbine :

REACTION TURBINES

Zl.,l Spiral casingThe water, from a penstock, is distributed around thc

guide ring in a casing. This casing is designed in such a waythat its - cross-sectional area goes on reducing uniformly around thecircumference. The cross-secfional area is maximum at the entrance,and minimum at the tip. As a result of this, the casing will be ofspiral sbape ; that is why it is called a spiral casing ot sooll cosing.The spiral casings are provided with inspection holes and qressurcgauge-s. The materiat bf a spiral casing depends upon the head ofwater, under which the turbine is working, as discussed below :

The guide vanes are fixed between two rings in the form of awheel. This wheel is fixed in the spiral casing. The guide vanesare properly designed in order to :

(a) allow the water to enter the runner without shock (This- is done by keeping the relative velocity, at inlet of therunner, tangentiai to-the vane angle).

(6; allow the water to flow over them, without formingeddies.

(c) allow the required quantity of water to enter the turbine(This is done by adjusting the opening of the vanes).

All the guide vanes can rotate about their respective pivots.The euide vanes can be closed or opened, by regulating shafts, tbusalloriing the required quantity of water to flow according to thcnecds.

2il'6. Turbine runner

ConcreteWelded rolled steel plateCast steel

22'5. Guide mechanism

The runner of afixed eithcr to a shaft or

Inpalse turbine

Thc entire availablc encrgy, ofthc water, is frst con:vertcd intokinetic cncrgy.

Thc water ffows througboozzleg and impiages onbuckets, wbich are 6xed tooutcr pcriphery of the wheel.

Thc water impinges onbuckets, with kinctic energy.

Thc pressure of the flowingwater rcmains uncbanged, andis cqual to thc atmosphericprcssure.

It is not essential that thewheel should run full. Morccvertbcre should bo free access ofair betwcen thc vanes and theshccl.

The water may be admittedoYcr a part of tho circumferenceor ovcr thc wholo circumfer-onco of thc whccl.

It is possiblc to rcgulate theflow without loss.

Thc work is ddnc ooly by thechango in thc tinctic energy of tbcJot.

Rcoction turbine

Thc availablc encrgy; of thowater, is not @nvert€d from orcform iatoanothcr.

Thc water is guided by thcguide blades to flow over thcmovlng vanes.

Thc water glides, oru thcmoving vaucs, with prerSurcencrgy.

The pressurc of the 0owingwater is reduced after glidiogovcrthe vanes.

It ir essential that the whcelshould alwayr run 'full, and kcptfull of water.

Thc watcr must bc admittedover the whole circumfcrcnce ofthe whccl.

It is not possiblo to rcgulate thcflow without loss.

The work is donc partlY bY thechanse in the vclocity head, butalmost entirely by tho cbange inprersurc hcad.

thethetbc

7.

lypor,whrtl

12.f, Clesslf,cation of reaction turbines

Radial flow turbines,

Axialflow turbines, and

Mixcd flow turbincs.

Thc rcaction turbines may be classified into the following threedopcnding upon the direction of flow ofwater through the:*

(a)(D)(f)


8/10

6n

22'9. Radial flow turbinesIn such turbines, tbe flow of water. is radial -(i'e' along the

radius of thc whcel). 'ifr; ti'Ji"r io"''iutbiott may Se further sub'divided into the foliowing two classes:

REACTTON TURBINES

(a) Inw a r d fl -w t u1 bin -^ - ]1 :11:3 -.t"tbj itti.:l; inwardsih; *h;;i "iihe outer PeriPhcrY

and

It may be noted that whencver the load on the turbine isdecreased, it causes thi shaft to rotate - at a -higher sp:ed' 'Thc;#;i?;A iit.", "iti"n- i*ttut"t due to the.higher

speed' l,tlgt to;;&;; t"h, q"uotltv or"*iiii-noiving over. the- vanes, and thus thcvclocity of water at th; ;;;i il ;t-:t. reduced' It will ultimately'tend to reduce tn" po*ii-dro-ou""a by the turbine. This is the;&;"";g;- ;i in-infiara fl6w reaction iurbine, that it adjusts.auto--"ti*ifi""tording toifti ttquited

load on the turbine' The higlcst;d;il;i i. Lut"i"Za,';h;;-i6 ;.iocitv or the leaving water is assmall as possible.

REACTION TI'RBINES6t,

2,2.t3. turbine

Y

2a2taz2--"

The efficiency or thc power developed 9y.th" turbine' mal b-cfouna o"ui

-tl dr*iog tne iittt and outle-t velocity triangles, as usudl,nr shown inFig.22',3.I,6t lz:Absolute velocity of the cntering water,

D-Outer diameter of the wheel,JV-Revolutions of the wheel per ninute'u:Tansential velocity of wheel at inlet (also

knoin as peripheral velocity at inlet)*DN: --60'

fz,:Relative velocity of water, to the whecl' atinlct

Vr:Yelocitr of flow at inlet"-

ii.r. iotu.Ot the centre of the whecl;'

(b\ Outward flowturbine' In- such turbines' the water enters

at the centre'#'tite-*ntil an-d- then flows outwads (i'e'io*"tat the'ouier periphery of the wheel)'

?,t'10" Axia flow turbinesIn such turbines; the water. 4ows -parallel to - the axis of

thc

whcel. Such turbin.t'"ii;"tto otled parailel flow turbines'

1l'l l. Mired flow turbinesThese are the latest types of turbines' in which the flow is

portly radial and PartlY axial.

tL'12. Inward flow reaction turbines

Ccnf.thrrl

w.n'2The inward flow reaction turbine' as thc namc indicates' is

tn"t ,rutioo'tooio, in-wniJn the-water entcrs thc whccl at tbe outcrocripherv and then frilffi".'4 Jver ^the vanes (r":' towards thoffiiT;i fri *i.iilas Phown inrig'22'2'

An inward flow reacfion turbine, in its simplcst form,.consistsor n";.i ilffbi;a;;ilr;h

-s"idi'-tle.water

to enter into therevolving wheel -at "otttti "odfe,

l'e' for the shockless entry ofwatcr. (This is ooot iV'-"ilui-ti"og'1|e vlne angle tangentially to

the

;&;i;t\,;ilttv olttt.'*"tir and the revolving wheel',- A: Y,*aiiiiiiJriliit"g, oi"i-ttt. vanes' cxerts some force on the revolvrngwheel, to which tnt ""nJs

ai; d;;ti: ihit fot"" causes the revolvingwhccl to revolve.

Fixcd


9/10

630 REACTION TURBINBSYv DvvT'

"" "1:::;:,T11[iJT: ll,ll'il.,s the wbee,,(also known as Guide blade angle),

9:Angle, at which the water leaves the wheel,0-Anglo of the blade tip at inlet (also known as

vane angle at inlet),

d:Angle of the blade tip at outlet (also known asvane angle at outlet),II:Total head of water, under which the turbine

is working),Z:Weight of the water entering the whcel in

kglsec.From the inlet triangle, we find that

V,:V cos u and V1:V sin aand from the outlet, we find that

Ya:V1 cos p and Vn:Vt sin Iwe know'-:try:#ffiT'Thirrs

(

z,- 2,,)x

(In this case,_Yois negative because V6 is in the oppositedirection as that of .Y,).

work done t:ffiilffiat inletxtangentiar verocity

of wheel at inlet;-(Velocity of whirl at outlitx tangential velocity of wheel at outlet)

:l-{r,r-Y,p;:S

-ryEnergy lost per * rt;;|l ilrt"rtbrough the wheel

zg

If there is no other loss ofenergy, thenV:n_Y*:.-ot_g_Ucszg

If tho discharge of the turbine is radial,9:90o'

Vrr:OYr:Vn'

REACTION TURBINES

Then work done per kg of watervrv:g

then V-o :H- 3cz8-H- 2tzg

631

...('.. tzqr-0)

...('.' Yr-VnlNote. trfthcvaves are radialatinlct,outlet or both,tbcn tbe vclocity

of whirl at that tip is zoro.Example 22'1. An inward flow reaction turbine, having an

exlernal diameter of I'5 metre runs at 400 r.p.m. The velocity offlow at inlet is I0 metreslsec. If the guide blade angle is I5o,find

(al the absolute velocity of water,(b) the velocity of whirl at inlet,(c) the inlet vane angle of the runner, and(d) the relative velocity at inlet. (Madurai University, 1972\Solution.Given. Dia. at inlet,

D:l'5 mSpeed of the turbine,

/V:400 r.p.m.Velocity of ffow at inlet,

Yt:lO mlsec FW 22.4Guide blade angle at inlet,

a: l5oWe know that the velocity of vane at inlet,

rDN zrx l.5I j99:31.41 m/sec- 60_:----60Absalute velocitv of water

Let Z:Absolute velocity of water.From the inlct trianglo, we find that the absolute velocity ofw&tcr.

,:#?, ...(... $ -einrc'):ffi:r8'88 m/sec Ans.

l'tloclty of whirl at inletLet Z":Velocity of whirl at inlct.lirorn the inlet triangle, we also frnd that the velocity of whirl

rrl rttlcl,V*:V cos l5o:38'88 x0'9659 m/sec

:37'56 m/sec Ans.

Y1

...(')

...(r,)

l.€.,thenand

F--+Vyr-

ts--D*---1


10/10

i{,I

I'Irl;lI

6?2 REACTION ITJRBINEIInlet vane angle of the runner

Let 0:Inlet vane angle.From the inlet triangle, we also find that

v, totan e -- ffi: 3756i3ml : r'626

0:58" 24' Ans.Relatlve

velocity at inletItt Zr:Relative velocity at inlet.From the inlet triangle, we also find that relative velocity at

inlct,

, Vt l0 -,^^^' : {inl5-g;T :o:EsI? m/sec:11;76 m/sec Ans.

Example 22.2 (5.1. units). An inwardflow reaction turblne hasouter ond inner diameters of the wheel as I metrc and 0.5 metre res-tectively. The vanes are radial at inlet and the discharge is radial atrutlet and the water enters the vanes at an angle of 10". Assuningthe velocity of flow to be constant, and equal to 3 rtetreslsec,find

(i) the speed of the wheel, and(Ii) the vane angle at outlet. (Calcutta Unlversity, Ig72lSoludon.Given. Outer diameter,

D:l mInncr diamcter, Dr:0.5 mAnglc, at which ths watcr enters

tho vancs,c:10

Vclocity of ffow at inlet,Y1:Y^-J slsss

Since the vaneg are radial at inletand outlct, therefore vclocities of whirlat inlet and outlet will be zero ; and theshapes of the two triangles will be asshown in Fig. 22.5.

I

Speed of thc wheelLet ff:Spced of the whecl in r.p.m.From the inlet triangle we find that the tangential velocity

whecl at inlet,

o:ffi-#:rzmlsec

Exmple 22.3. An tnward flow reaction turblne ls suoollcdwater at the rutc o16 0 litreslsec with a velocily of flow of 2'ii1sec.'r'he-velocity of perlphery and velocity of whirl at -inlet is 2l ritsecan( I mlsec. Assyming the discharge to be rudial at outlet, and'thcYelocity ofllow to be constant, find

(I) vane angle at hlet,

RBACNON TI'RBINEq

We know that the tangential velocity of wheel at inlct*DN,:6

,y-$ -gx{:325 r.p.m. Ans.

L€t C:Vane angle at outlet.Wc know that the tangcntial vclocity of wheel at outlet,,,:$tr:*# I:8.5 m/sccFrom the outlct triangle, we fnd that

tan 6: b-gl=o'rsgg:lf 27' Anr.

(21 head of water on the whecl.Soludon.

Givcn. Dicchargg,n:ff;Jji?l'*

Vclocity of flow at inlct,y1n2 mlscr

Velocity of poriphcry at inlct,u:24 m/scc

Velociiy of whirl at inlct,

. P':18 m/sgcVclocity of.flow is constant, i.a.,Yt:vn

Yane angle at inletL€t 0:Vanc anglc at inle1.From thc inlet triangle, we find that

(Poona Universtty, 197 3)

tan (l8f - o) * 3_: #r-0.3333(180":f):18" 26'

0: 16lo 34' rAns.

or

Ymc angle at outlet

f

|_-"--l

>.

of

Documents

Water Turbine-1 - Copy