Raabe J. Hydro power - the design, use, and function of hydromechanical, hydraulic, and electrical еquipment

Подождите немного. Документ загружается.

ge~~eration of a difference

level upstream of the dam and downstream of

it.

This level

difference is nearly the

net

head. The high head thus created generates then the economi-

cal high velocity of the fluid to drive a turbine of economically high speed.

In the case of a run-of-river and barrage power plant, including submersible power plants the tail

water lies adjacent to the dam. In the case of a diversion power plant a loop of the river is

short-circuited by

canal or closed duct. Thus the tailwater now is far away from the dam. The same

holds for a transition power plant with the difference that now the

diversion

joins another river

system, or a tributary of the original river from which the diversion has been branched off, see

[1.52

to 1-54].

In the exceptional case of a plant with free stream turbines no damming device is needed. There only

the head

dc2/2

is harnessed by diffusion in the draft tube of turbine, Cap. 10.2.

1.6.1.3.

Depression power plants

In these plants the water is diverted from the ocean into a depression of the continent,

located near the sea and below the sea level in a hot desert'for example, so that

thf: water

evaporates from the surface of this tailwater reservoir to such a degree that its level is

retained in altitude.

project will probably be made in the Cattara depression in Egypt

near the Mediterranean Sea and Cairo,

poteiltial

5.7

TWh

[1.50;

1.53; 1.55aj. Another

project exists for the Dead Sea also fed from the Mediterranean Sea.

similar kind of depression can be created, if an estuary of an ocean, surrounded by a continent

and hence heated more and evaporating more quickly than the adjacent ocean, is separated artifi-

cially from the latter by closing the straits with a barrage. Such a project,

e.g. in the strait of Gibraltar,

would lead, owing to unbalance between inflow by rivers, rainfall and evaporation to a lowering of

the level of the Mediterranean Sea relative to the Atlantic Ocean.

The same would result from a barrage in the strait of Bab el

Mandeb, which separates the

Red

Sea

from the Indian Ocean. According to

Mosonyi

[1.53] in this case the level of the Red Sea would

come down relative to that of the Indian Ocean by 2,5 m annually. Within 20 years this would create

head

50 m. After this period, supplying the plant with annually evaporated water, an annual

output of about

130TWh could bc generated, that is, sufficient for Italy in 1974. However, the

estimated dam volume of about

2. lo9 m3 and the environmental impact of such a project, with

consequences on the adjacent coast which are not clearly known and the absence of local energy

demand, make such a project castles in the air.

1.6.1.4.

Wave energy

Wave power is a form of wind power when the waves result from the effect of wind.

According to

Simeons

[IS5 a] the total available energy within the United Kingdom's

territorial waters has been estimated to be greater than twice the present installed

capacity of British power stations. Fortuitously the seasonal peak matches electrical

demand.

In Sweden, the theoretical wave power potential along the 2200 km coastline is estimated at 45 TWh

annually. The percentage time, when conditions permit extraction of wave energy varies from 60%

in the north of Sweden to

100%

in the south. According to

Simeons

[1.55 a], a wave power plant in

Sweden is

asstimed to consists of 6700 concrete buoys each with a diameter of 3 m, some

km from

shore and at a depth of some 30 m. Each generator produces AC which is immediately converted

into

and led to a converter on the shore. Interest rates have been assumed at 10% with 25 years

write off time giving a price per

kwh of

0,14

to 0,23 Swedish crowns.

comparison between a 20

Diesel plant and a 20

wave power plant shows that the capital

cost per

in the wave power plant is about

times higher than in the Diesel plant, whereas the

operating cost of the latter is 50% higher than in the wave power plant.

To ctate Irtrger wave

power

plants cxist only as projects.

'rhe

safc and

efficient

Jcsign of

wavc cnergy systems requires

solution of the following proble~ns:

Accurzte prediction of the wave-induced motions and loads, mooring forces, extremc

loads, likely fatigue damages.

Evaluitting structural responses which tnny include clestructive testing.

Simulating structural designs, reliability and minimum life.

Countries involved are Australia, Canada, China, Egypt, Finland, Japan, Mauritius, Norway, South

Africa,

Sweden, Lrnited Kingtlon~, USA, USSR.

Over the years, many dcvices havc been patented with the object of extracting energy

from thc waves. These includes converging channels, flaps, floats and ramps, but 'many

them have failed because they did not operate on the principle that, in

wave, each

particle of water approximately moves at

constant speed in a circle.

The effectiveness ofa tloat or other dcvice depends on its shape.

fixed body will pi-event ivavesfrom

developing behind, the waves being reilectcd alrnost totally after impact. I-lowcver,

frce movement

is pcrmittcd with the waves. the reflection no longer occurs, a wavc being transmitted behind the

float. 111 neither case will power be extracted. The approaching waves rnwt bc absorbcd coupled with

the absence of any wave

bcliind the device

power is to be recovered.

For this purpose a rocking beam was proposed by

Salter

[1.55

a]. Here the float (Slllter's

duck) has

front scrface which moves with the water of the oncoming wave and a back

surfacc that does not disturb the water behind. Thus the float rocks about its axis and

this

n?ution relative to

neighbouring body, not rocking, has

be convcrted into electric

energy.

There are numerous ways in which power can be derived from the slow oscillation caused

wilves.

One means to consider is converting the motion of waves into uni-directional

iligli

pressure water pulses by rncans

a teversi~lg pump.

One of the problems is the means by which the power generated is to be brought ashore.

This could be achieved

throu_gh the use of flexible submarine cables or alternatively water

might be pumped at high pressure from floats at sea, with the electricity then beicg

generated

land.

Maquda

ill

Japan

j1.55

has developed an air pressure ring buoy. This is open at its bottom from

allici.1 air is displaced rhythmically by the wave action. The air flow is rectified by

Flap

valves and

used to produce power through a low pressure air turbine.

Another device, Russel's rectifier

[1.55

a] is composed of a series of high level and Igw level reservoirs

both of which

are exposed to waves. The reservoirs are separated from the sea by

set of vertical

return flaps so that waves drive sea water into the high level reservoir and extract it from those at

the lower

level.

turbine is instelled between both the reservoirs.

In Mauritius wave energy is extracted on the principle of a wave run-up over a contoured wall

sloping

30",

behind which the water becomes entrapped to a head water reservoir.

The Lancaster flexible bag has a number of cells which are formed in a long tube of flexible material.

The tube

open along its lower side and sealed to a rigid and moored beam, in which two air mains

are formed. When a

\\lave rises around a cell, it forces the air from it into the high pressure nuin of

the

beam. As the surface

the vicinity of the cell falls, the pressurs within it drops until air flows

into

from the low pressure main. Air then returns from the high pressure main to the low pressure

main via an air turbine,

[1.55

a].

The Vickers energy converter

[IS5

a fully submerged device likely to be mounted on the sea bcd.

This arrar?gements avoids the problems of mooring normally associated with floating devices. Here

rcsonnr.tly oscillating mass of water

excited by the changing static head of the wave passing over

it.

The function of this device does not depend on the direction

wave propagation.

Whittirlgton

and

Wilson

j1.561

have developed a model for generation of steady

output from

variable wave power by means of an induction machine and

sy~~chronous machine, both couplcd

electrically.

Besides the wind-induced waves. there exist also tide-induced waves and sea-quake-

induced waves.

1x1 general, the wind-induced waves have the shortest wave length. All

these waves are superimposed to each other.

the Pacific Ocean e.g. along the Japanese coast occasionally sea-quake-induced waves,

the so called

Tsunamis may attain amplitudes up to

m. By the impact pressure of such

Tsunamis waves on steeply inclined coasts the water due to the wave may be lifted

into

artificial reservoirs. From these the water then may propel a water turbine.

1.6.1.5.

Tidal power piants

These plants harness the tidal range of the oceans between ebb and flood. This effect is

caused mainly by the mutual attraction of moon and earth when rotating with a nearly

monthly period around an axis 'a' (see Fig.

1.6.1) through their common centre of gravity

orientated normal to the plane of the lunar orbit.

being accidentally underneath the

earth surface.

Fig.

1.6.1.

Generation of flood humps.

earth,

moon;

common centre of gravity moon-earth;

flood hump

due to centrifugal

force;

flood hump due to gravity

force;

axis of rotation of the earth-moon system;

earth

axis;

plane of lunar orbit and approximately also that of

the

earth orbit;

---

imaginary spherical earth surface;

weight;

F.,

centrifugal force;

gravity force of moon;

resulting force on body on the earth normal to the sea

surface;

parallel to axis

latitude.

Along an earth diameter parallel to 'a' (see Fig. 1.6.1) the centrifugal force induced by

rotation around the above axis 'a' and the lunar gravitational attraction are balanced.

Therefore the resulting force on a fluid

elenlent at the ends

and

of this earth diameter

points towards the centre of the earth

Hence a fluid element at these stations remains

with its surface parallel to the earth's surface. For a liquid element on the side away from

the moon the centrifugal force due to rotation around the axis 'a' is stronger than the

lunar gravitational attraction.

Hence by static equilibrium the ocean surface there deviates slightly from the nearly

spherical original form, creating a hump oriented away from the moon. On the opposite

side of the earth oriented towards the moon the more influential gravitational attraction

of moon forms as a whole a liquid hump, pointing towards the moon (see Fig. 1.6.1).

As a whole the surface of the oceans has an oval deformation along

the connecting line

of earth and moon. The earth itself rotates around its spatially fixed axis once a day.

Therefore every point on its liquid surface passes within approximately one day the flood

hump, caused by the gravity of the moon and then 12 hours later the hump caused by

rotation of the earth around the axis 'a' (see Fig. 1.6.1). From this it is also seen that

thcse

two flood humps usuaIly cause at any instant at a point of a certain latitude on the earth

spccial tidal range. This depends also on the angle

the earth's axis makes with

the

connecting line

of earth and moon, see Fig. 1.6.1.

When this ;~nglc !~ccoriics

00'

nrc 1i;ivc t!ic equinox

'1.

Now

the

stations on

average

latitude

cross t\\.icc

<l;~;iy

~icarly tI!c sll~nmit of

both

thc Ilood humps. Consccliicntly this

i'rcqi~c~i~ csci t;itio~i

tiic (lccalis cliiri~i~ the cquinox in cc:.nncction with the cigcn-

fri*ql~cncy

rhc 1i11,gc \;.:Itcr nlasscs

;it

tlic ;\tlantic coast of Europe and Southern Canada

rcsrilts i~;to tlic iiiglicst tiilal range.

the polar rezion, especially in surnmer or winter,

this

niodcl gives only

onc

flood d:tily. which is what happens.

similar interaction exists between earth and sun. I-lere the common centre of gravity

the system

tlic sun. For thc s:me effects, as described cbove, two flood humps are

generri~ccl at the ctcenn in the direction towards the sun and away from it. They are

n;itiirally

smaller

than the two due

isltcl-action of earth and moon. Both pairs of humps

have to be

;ldclcd \vlicr, earth and moon are along a straight line during new moon and

fiifl

moon. 'l'hcn tllc highest tidal r;inge occurs, the spring tide. When the earth is on the

corner of

I-CCI;III~IC

formed by sun, moon and earth, then both the humps have to be

subtracted

fro111 e:ich other. Now the lowest tidal range occurs, the neap tide.

Considerin?

only

the action

tlie nioon, the highest tide-conditioned sea level has to

occur.

accordin_c to llle static consitleration made so Par, when the moon passes the

meridian.

T!I~s

ill

fact is retarded owing to the inertia of the large water nlasses by about

six hours in our

I;~titudc.

Adding

the

informaiion

givcn

[1.55

a].

the usable potential of tidal power

may

estimated

the

OJ~C~

0;'

1000'TWh. 1-he average tidal range

the opcn occan is very sm;ill below one

metre.

The

cffcct bcconles renlarkable by the impact of a tidal wive on cst~raries and straits iis for example

the

Cf~anncl bctn.ccn France and

Britain..

111

the

latter case,

the

:ide-conditioncd flow between

the

Atlantic Occon

and

ihc Gcrmzn Sea at the instant the tidal flood wave entcrs

the

Channel, causes

Coriolis

force.

This

lifts tlic ivater additionally

the Etiglisli coast and lowers

the French.

The

addiiionai

ram

cffcct

convergent estuary adequately oriented

may

lift

the

tidal range during

spsins

tide

i;t

thz

<tj~ii~~\)\

LIP

to 13!5

the river mouth of

the

French Ratlce and up to

m in

thc

Car~adiari

1-und!

B;:y

thc

North Atlani~c coast, sec

Slra\r,

[1.57]

and

1-or!.

[1.58].

There

the

largcst tidal poiicr

unit

insrnlled

rhc power station .+\nnapolis (see

Fig.

10.2.21,

22).

of the

Straflo

design

wi:h

rim

Fncr:itor, which

senr~inely best fitted

for

llarncssing tidal power, and built

:tf:sr

the dcsigns

Sa~zcr

Eschcr Wyss the patentee, see

Do~cnln,

Steworti

and

Meier

[1.59].

Also

lr~dian

tidal

power projects were discussed by

Sharnzil.

[1.60]

ruld

Subrahmc~nyml

[1.61].

Problems and be~siits of tidal power stations are considered by

Benn

[1.62].

tidal poiver p;ant [nay be equipped with one or two basins. The one basin type which

is the only

type

bui!t to date (see Fig. 1.6.2) may have one flow direction (single effect) as,

e.g. in clnnapolis. This guarantees hig!lcst efficiency with the slight disadvlrntage of either

great storage kolume or limited working period. More see Cap.

10.2.

Thercforc the Frcnch firm Ne~rpic, Grenoble, has developed, for the Rance tidal power

plant

(see Fig. 10.2.13, and axial bulb turbine that operates with one basin

both the

flow

directions both

a turbine and as a pump (double effect scheme).

The action

such a tidal power plant as the Rance

with

one basin and double action (reversal of

turbine

flow;

considcrcd more

detail (see Fig.

1.6.2).

Owing to the tides, the ocean le\lelO moves

nearly

h:irmo~:io~~sly vs time.

its highest 1e;lel

is connected with the basin

sluice then

opencd.

Wht-n

the cicenn level begins to lower, the sluice giltcs are c!osed.

a reasonable difference

height

water Icvcls in basin and occan, thc set starts turbining from the basin to the ocean,

period

Before ebb

the

sct is shut down. The sluice gates, then opened cqualizc the level of the ocean

and

basin.

Strictly

speaking

this

holds

true

only

the

pl;uics

the

orbits

sun

and

moon

are

coincident.

Fig.

1.6.2.

Time sequence of

operating

modc in

tidal power

plant with double effcct:

waiting:

filling; 3 direct turbin-

ing; 4 revcrscd turbining;

emptying (sluicing);

ocean

Icvel; b basin level; c basin level with pumping.

hours

When a reasonable head between the rising level of thc ocean and that of the basin for the second

cycle of power generation (period 4) has bccn reached, the machine begins to operate as a turbine

with reversed flow direction from the ocean to the basin. For more details see Cap. 10.2.

1.6.1.6.

Hydro power from gas washers

The principle of these plants can be seen in Fig. 1.6.3. Pressurized waste gas charged with pollutants

is exhausted from a process. For the purification of this gas and the use of its energy, the gas flows

into a closed vessel and is sprinkled with pressurized water circulated by an impeller pump. By this

and Raschig-rings, the gas is adsorbed by water. This then operates a turbine. Past the runner in the

low

pressure zone the gas comes out of solution. The clean gas then is removed from the top of the

tailwater tank and its impurities from the bottom of the latter. The surplus of turbine output over

the impeller

pump's input drives a generator [1.50].

Fig. 1.6.3. Scheme of a gas washer: 1 purificd water pres-

surized; crude gas polluted and pressurized; 3 Raschig rings;

washing line;

polluted water pressurized; 6 polluted water

pressure-relieved;

separator;

purified gas;

sludge

pocket; 10 clean water pressure-relieved;

turbine;

alter-

nator; 13 impeller pump;

sprinkler; (Scheme courtesy

Vevey Engineering Works, Switzerland).

1.6.2.

Plants for conversion

secondary energy

These

called pumped-storage plants use secondary energy in the

form

electric energy

for storing it

potential encrgy in an elevated artificial reservoir. In these plants cheap

base

load energy

from

plant converting primary energy (e.g. run-of-river

thermal

power plant) is

used

to pump water from

tail

water

basin into an artificial head water

basin. The water potential thus generated is used, to

cover

expensive peak load demand.

European aspects of pumped storage were discussed

Angelini

[1.63], the Japanese by

Okada

[1.64],

some Swiss aspects by

Stiirzinger

[1.65] and

Rochat

[1.66]. Hernan considers Dinorwic, Great

Britain's biggest binary plant

[1.67].

Meier, Miiller, Grein

and

Jaqrret

[1.68] give information about

recent binary and ternary sets in Western Europe. Similar projects in Italy are

rcported by

Magnago

and

Bortolan

[1.69].

Pumped

storage plants were equipped originally by ternary (or tandem) sets with

spccial impeller pump, turbine and motor-generator along the shaft (see Fig.

1.6.4

a). As

consequence

rises in wages and

hence

initial cost

the power house and its

equipment, nowadays binary sets are preferred with pump-turbines

the only hydraulic

Fig.

1.6.4.

a) Double flow 2-stage storage pump, horizontal shaft, and torque converter for synchro-

nizing and speeding up the water

fillcd pump of pumped storage plant with ternary sets, Wehr,

Wehra, Federsl Kejjublic oi Germany (West Germany) (Owner Schluchsee

AG.

ITrciburg) built by

Voith, Heidenheim. Data of pump:

640 m,

m3/s,

600 rpm,

248 MW;

torquc converter

150 MW (water filled). Pumps belong to 4 ternary sets with Francisturbines

sholvn in Fig. 10.3.10 built by Sulzer Escher Wyss. To date the most powerful plant with ternary scts

(Draning cotirtesy Voith).

machine on the shaft of a set (see

Fig.

1.6.4

b).

Also plants for the harnessing of water

pawer petential

have

been equipped subsequently

with

pumpzd-storage sets (see

Fig.

1.6.9).

ternary

100

set of about

300

head riow may reach a storing cycle efliciency of

'77%

(sce

Fig.

1.6.5).

corresponding binary set shows

drop of this efficiency

about

and hence

shortage of revenue corresponding to the capitzl expenditure

sets. efforts have been made to reach greater compzctness with the ternary set

(see Fig.

1.6.6).

Greurest compactness in ternary sets is effected by the so called "Isogyre" design (Fig. 1.6.7 (1.701).

Invented by the firm Ateliers de Charmilles, this design is now exclusively built by Vevey Engineering

Works Ltd, one of the oldest turbine makers of Switzerland, who many years ago were affiliated to

Fourneyl-on,

the

pioneer of modern hydroturbine engineering. Also

Girard,

inventor of the first

usefiil impulse turbine, worked there.

Fi?. 1.6.4. b) Elevation of pump-turbine set at Kiihtai, Austria (owner Tiroler Wasserkraftwerke),

built by

Voith, West Germany. Data

600 rpm;

319 to 440 m. With one set: turbine

mode

87,5

to 151,3

MW,

pump mode:

124 to 109,4 MW; with

sets: turbine mode

82,s to 143,s

MW.

pump mode

123,7 to 108.5

MW.

Spiral casing free of external forces by

means

a Sulzer Escher Wyss type load compensator (see Fig. 3.4.44) and

embedding

sponge

rubber. Gates opornted by sitlgle servo motors, electro hydraulic controlled; we;ded spil-a1

casing with a stay ring of ncarly parallel plate design, 3 guide bearings. Thrust bearing supported

spidcr ;tbovc the alternator. Start up into pump mode with dewatered rotor in air by means

pony motor within 90 s. Pony motor

MW.

Total weizht of the set 940 tons, weight of

the

rctatlng parts 287 tons,

fly

whcel moment

GD'

1195 hlpnli (drawing courtesy

Voith).

k'ig. 1.0.5.

.t~sscs ;rntl cffici~~lcics of

tcrn:Iry (tan-

tlc~n) sc~

I>III~IIIXJ-SIO~;I~C ~)l;in~; cs;i~nplc

Vi;in-

?..

tlc11.

.IIXCI~~~III.~ (cn\.ncr

SociCtC

d'i:lcct ricilc d'0ur);

'.--

scls: tir~.t~inc~

2x7

111:

42X.6

rpm;

105

bIW;

punlps

2S7

MW.

Losscs

'.i7

3,~

duri~is ~r~rhiliing:

penstock.

ti~rbinc,

gcncrator.

0.5

.,{

trunsfornlcr. 1.osscs cturing pumping:

pcnstock;

pu~iip; 7 rnotor;

tr;lnsforriisr (Drawing Socikti:

L--I-.A

d'klcctricit~; d'Our)

10J

Fig. 1.6.6.

:11

Elcv:ition of a vertical shaft tcrnary pumped storage set. Waldcck

(owner

PrcusscnclcLtra-\I.:~sscrkraftanl;n

GmbH Hannoverl:

sets: Francislurhine

(FT),

built by Voith:

336

rn:

-375 rpm:

239

MW;

1-stage pun~p(P) bull(

Sulzer Eschcr Wyss:

330

At\\'.

I-or hiphcr sub~ncrgcncc the pump should bc undcrncath thc turbine. Overhung

cicsign

hcth

rotors lowers cost. To eliminate disk friction of labyrinth rings on cmptied pump

impeller. rad~al cle;irance of

staircase

labyrinth is incrcascd by lifting stationary labyrinth ring

hydr;iulic;ill!. hxial thrust bcari~ig on pump head covcr. Motor

generator

badly accessible.

Dctail of purnp section (Dratvings courtesy Sulzcr Escher Wyss, and

Voith).

Fig. 1.6.7. Elevation of vertical shaft "lsogyre"

Anstrim Malta scheme (owner

(jsterreichische Draukraftwcrkc

AG,

Klagen-

furt), upper stage, also provided for pumped-

storage.

sets. Runner (above) and impeller

(below) in back to back arrangement

with

spiral casing givc the most compact ternary

set. Flow reversal in the toroidnl dilTuser of a

pump. Built

Vevey Charniillcs Engineering

Works. Pole changing motor generator built

by Brown Boveri. Data:

turbining with

500 rpm:

129 to 220

36,4 to

MW;

with n

375 rpm:

60 to

129

11,3

to 36,3

MW;

pumping with

500rpm:H

109,5 to200m;

46,710

46MW; with n

375 rprn:

109,5nl;

18,4

to 19,9MW; D=2m

(Drawing courtesy Vevey Charniilles Engi-

neering Works).

The Isogyre design has a pump and turbine rotor back-to-back. For economical reasons

both are connected alternately with the same spiral casing and suction flange by means

of cylindrical gates.

retention of speed direction during both the modes of operation

guarantees a short transition period. Hence a given sense of the spiral casing requires a

reversal of flow by

180'

for one of these services.

This

is done very effectively on the pump

side by means of

bladed toroidal diffuser channel so known from the multistage impeller

pump-

symposium was dedicated to the Isogyre

-7 11. The latter was described by Fauconnet

.72]. The

owner's view on this design is revealed by

Widnlann et al.

(1.731,

and Hautzenberg [1.74].

certain disadvantage of pumped storage plants lies in the fact, that peak load demand exists

usually in the densely

populated

industrialized areas, mostly located in flat regions.

the other

hand the storage volume of the upper, usually

artifical, reservoir for

certain work per cycle becomes

smaller with increasing head and with it also the cost per

kW.

The head range at present is between

and

1600

m (San Fiorano in Italy, see Figs.

1.6.8

and

1.6.9).

In West Germany many of these pumped storage schemes, some dating back

Fig.

-I

.6.S.

Elcv:itinn of

6-stagc storage

ternary

punlpcd-storage sctc, Sun Fiorauo,

1t:lly (owncr It;~lia~l

Electricity

power boilrd

I'N

[?I.)

built by dc I'rctto Eschcr Wyss. Dat;~:

)I,,

1453,7 ni;

600

rprn.

105.8

M\V,

2,l

m. To datc higlicst dclivcry head of

pumpcd-storage (Drawing courtesy Sulzer

Eschcr Wyss,

Switzerland).

1910

(Brun~enmiihle),

arc

locatcc!

mountainous southern area far fro111 the

large

consumers

the northern Rhine

Ru!lr

region.

They

need thcrefore

long and expensive

high

voltage line

about

800

360

kV.

save such expenses and for making thcse pumped-storage plants indcpendcnt of the topography

of industrialized

arcas, it

has

been proposed to use subterranean caverns as tail water basins, e.g.,

abandoned coal mines.

the West German Ruhr region the latter may have a depth of

1000

more.

1.6.3.

Hydro

powrr

transmission drives (torque converter)

Thcse gears are an invention of the German

Fottinger,

1905.

They consists of a turbilie and

impeller

pump short-circuited with a guide apparatus in between. This enables the differential torque

berrveen the input and output shaft to bc led ii:to the ground. Bccause of the absence of

diffuser

the

eficiency is quite high but below that of a-toothed wheel gearing. Therefore the use is limited

to gear changing.

The high density of fluid and heads up to

bar per stage enable

high power

density. For

cxtmple the water-operated synchronizing torque converter of a

250

hlW

ternary set

1Vehr (West Germany) has a turbine part with a centrifugal runner (after Fourneyron) with about

2.3

m tip diameter and up to

lbO

output (see Fig.

1.6.4).