water wheel turbine
TRANSCRIPT
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Water-supply and
Irrigat ion
P s . p f ? N u . 1 8 0 S er m
M ,
G e n e r a l H ydrographic Invest igations, 1 8
DEPARTMENT OF THE INTERIOR
U N IT E D ST AT E S
GEOLOGI CAL
SU RV E Y
CHARLES D. WALCOTT,
DlKECTO
TURBINE WATER-WHEEL
TESTS
AND
POWER TABLES
BT
ROBERT
E HORTON
WASHINGTON
GOVERNMENT PRINTING OFFICE
1906
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Water-Supply
and Irrigat ion Papef N o . 1 8 0 Series M , General Hydrographic Inves t igat ions , 1 8
DEPARTMENT OF THE INTEEIOK
UNITED STATES GEOLOGICAL
SURVEY
CHARLES I). WALCOTT, DIRECTOR
TURBINE WATER-WHEEL
TESTS
AND
POWER
TABLES
BY
ROBERT
E HORTON
WASHINGTON
GOVERNMENT PRINTING OFFICE
1906
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CONTENTS.
P a g e .
Introduction.............................................................. 7
Principal types
o f
water
wheels.............................................. 7
Ve r t i c a l water wheels.................................................. 8
Classes o f
turbines.....................................................
9
Tangential
outward f low turbines Barker's
mll......................
9
Radial
o u t w a r d - f l o w
turbines the
Fourneyron
turbine................. 9
Parallel d o w n w a r d - f l o w turbine the Jonval turbine................... 12
Radial
i n w a r d - f l o w
turbines the
Francis turbine...................... 13
Mi x e d - f l ow turbines................................................ 13
S c ro l l central-discharge wheels.................................. 14
A m e r i c a n type o f turbines...................................... 14
T y p e s
o f
turbine
gates
a n d
guides....................................... 16
M e c h a n i c a l
p r i n c i p l e s o f
the
turbine..........................................
17
H o r s e p o w e r
and
e f f i c i e n c y o f
turbines........................................
19
T u r b i n e
testing............................................................
2 2
G e n e r a l
review.......................................................
2 2
C e n t e n n i a l tests.......................................................
24
Tests by
James
E m e r s o n , and the H o l y o k e hydrodynamic experiments.......
30
Tests by
H o l y o k e
Water
P o w e r
Company................................
36
G e n e r a l discussion.................................................
36
Detailed tests..................................................... 41
M c C o r m i c k turbines...........................................
41
Hercules turbines..............................................
60
S a m s o n
turbines...............................................
66
N e w
A m e r i c a n and
S w a i n turbines............................... 71
T h e
u s e o f
the
turbine
as
a
water
meter......................................
7 6
Reliability
o f H o l y o k e
tests a s to turbine
discharge........................ 77
Variation in
d i s c h a r g e
f o r d i f f e r en t
w h e e l s
o f
s a m e
pattern.................. 7 8
Variation in d i s c h a r g e f o r d i f f e r e n t w h e e l s
o f
the s a m e type................. 7 9
Variation o f
turbine d i s c h a r g e
w i t h speed................................. 80
Variation
o f turbine c oe f f i c i e n t s w i t h variation in head..................... 81
M e t h o d s
o f
turbine setting
and
arrangement..................................
82
Turbine plants
f o r
varying
head............................................. 85
C o n d i t i o n s
g o v e r n i n g e c o n o m y i n
s ize
and number o f turbines used..............
85
Manufacturer's tables
o f
p o w e r , s p e e d , a r i d discharge...........................
87
G e n e r a l
discussion.....................................................
87
Rating
table
f o r
Fourneyron turbines................................
94
McElwain.................................................... 94
Rating
t ab les fo r sc ro l l c e n t r a l - d i s c h a r g e
turbines.
.....................
95
John Tyer................................................... 95
Reynolds..................................................... 95
C ar l ey helical................................................. 96
Perfection.................................................... 96
Jones Little Gant.............................................
97
3
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4
CONTENTS.
Manufacturer's tables
o f
power, speed, and
discharge Continued.
P age .
General discussion Continued.
Rating
tables
for Jonval turbines....................................
9 8
McEwain.................................................... 9 8
Bloomingdale, or Wait's Champion..............................
9 8
Dx.........................................................
9 9
Osgood....................................................... 9 9
Bodine....................................................... 9 9
Chase........................................................ 1 00
Rating tables
for
register-gate
turbines............................... 1 01
Gates Curtis.................................................. 1 01
Eclipse
double................................................ 1 01
Helmcr's patent Rome......................................... 101
C a s e National................................................. 1 02
Wtmore..................................................... 1 02
Flenniken.................................................... 1 03
Humphrey
standard
IXL...................................... 1 03
Humphrey
standard XLCR.................................... 1 04
Burnham's
n e w improved......................................
1 04
Balanced
gate.................................................
1 05
Alcott's
high duty............................................ 1 05
Lesner's
improved.............................................
1 06
Risdon.......................................................
1 07
Rating
tables for pivot-gate
turbines.................................
1 08
Crocker......................................................
1 08
Camden horizontal............................................. 1 08
Camden vertical............................................... 1 09
Camden
steel
double ...........................................
1 09
United Sates................................................. 1 09
C o l e Domnion................................................
1 1 0
Badway.................................................... 1 1 0
Bartley water-tight............................................ Ill
Canada....................................................... Ill
Emer........................................................ 1 1 2
Eureka....................................................... 1 1 2
Smith
improved
Success....................................... 1 1 3
Smith
n e w
Success............................................. 1 1 4
American..................................................... 1 1 4
New
American................................................ 1 1 5
Poole
& Hunt
Letfel...........................................
1 1 6
Trump model.............---.-...--..----..-....-..-.........
1 1 7
Leffel........................................................ 1 1 7
Le f fe l
Samson................................................. 1 1 9
Rating
tables for
cylinder-gate
turbines...............................
1 1 9
Rochester.....................................................
1 1 9
Swain........................................................
1 2 0
Dolan's Little
Gant............................................ 1 2 0
Dolan's
Improved
Little
Gant..................................
1 2 1
Hunt Standard, n e w pattern.................................... 1 2 2
Hercules...................................................... 1 2 2
McCormck..'................................................ 1 2 3
McCormick's New England...................................... 1 2 3
Taylor sleeve-gate.............................................
1 2 4
Vctor........................................................
1 2 4
Victor
high-pressure............................................ 1 2 5
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CONTENTS.
5
P a g e .
Lterature................................................................ 1 2 6
Hstorical.............................................................
1 2 6
Descriptive........................................................... 1 2 6
Ve r t i c a l water
wheels...................................................
127
Turbines.............................................................
1 27
T u r b i n e design....................................................
1 27
A m e r i c a n type o f
turbine...........................................
12 8
Mathematical
theory o f turbines..................................... 12 8
Turbine governing................................................. 1 29
I m p u l s e
water wheels.................................................. 1 30
Index................................................................... 131
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I L L U S T R A T I O N S .
PLATE I.
A,
Recent American
type o f
water-wheel runner; B, Dynamometer,
Hoi-
yoke testing
flume..............................................
1 4
II.
A,
Turbines o n horizontal shaft; B, Pair o f
turbines
o n
horizontal shaft.
8 2
FIG.
1. Section
o f
Fourneyron
turbine........................................
1 0
2 .
Plan
o f
Fourneyron
turbine..........................................
1 0
3 . Double Fourneyron
turbine at
Niagara Falls........................... 11
4 . Section
o f
guides and buckets,
Niagara Fourneyron
turbine.............. 1 2
5.
Section o f
Francis center-vent turbine.................................. 1 3
6 .
Section
o f
runner
o f
Francis
center-vent
turbine........................ 1 3
7 . S c h i e l e
turbine.....................................................
1 4
8 . C r o s s
section
o f early turbine with
deep
bulging buckets, pivot gates, and
an adjustable step bearing...............
......_... _...............
1 4
9 . Diagram illustrating principle
o f reaction.............................. 1 7
10.
Diagram showing impulse against curved vanes......................... 1 8
11.
Diagram
illustrating theory
o f
moving
vanes...........................
1 8
12.
Diagram
showing
interference
and eddies in a
turbine...................
2 2
13.
Diagram showing e f f i c i e n c y o f
various
prime movers.................... 2 3
14. C r o s s
section
o f
Holyoke
testing
flume.................................
3 7
15.
Log
o f test o f 3 6 - i n c h Hercules turbine, fu l l gate........................ 3 8
16. Log o f test
o f
36-inch
Hercules turbine,
0.806
gate......................
3 9
17.
Log o f
test o f 3 6 - m o h
Hercules
turbine, 0 . 6 4 7 gate......................
3 9
18.
Log
o f test o f 36-inch Hercules
turbine,
0.488 gate...................... 4 0
19. Log
o f test o f
36-inch
Hercules
turbine, 0 . 3 7 9
gate......................
'
4 0
20.
Proportional discharge
c o e f f i c i e n t s ,
12- , 15- , 18- , and
21-inch
M c C o r m i c k tur
bines.
...........................................................
4 1
21.
Proportional discharge c o e f f i c i e n t s , 2 4 - , 2 7 - , 3 0 - ,
and
33-inch M c C o r m i c k tur
bines. ........................................................... 4 2
22. Proportional discharge coefficients, 3 6 - , 3 8 - , 42-,
and
45-inch M c C o r m i c k tur
bines. ...........................................................
4 2
23 . Proportional discharge coefficients,
4 8 - ,
51- , 54- , and
57-inch
McCormick tur
bines.
........................................................... 4 2
24 . Proportional discharge
coefficients,
Hercules
turbines.................... 6 0
25. Proportional discharge c o e f f i c i e n t s , Leffel-Samson turbines.... .. . ......... 6 6
26. Efficiency
curves,
Lefl'el-Samson
turbines..............................
6 7
27 .
Proportional
discharge
coefficients,
N e w
American
turbines.........'......
7 1
28 . Part-gate discharge c o e f f i c i e n t s for three 24-inch Hercules turbines........ 7 8
29. Types o f part-gate discharge
coefficient curves..........................
7 9
30. Variation o f turbine discharge with
speed,
24-inch M c C o r m i c k turbine....... 81
31.
Variation
o f
turbine
discharge with speed, 42-inch M c C o r m i c k turbine..... 8 2
32. Variation o f turbine discharge
with speed, 54-inch
McCormick turbine..... 8 3
33.
C r o s s section o f
power house
near
Geneva,
Switzerland
..................
8 4
6
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8 TCTEBINE WATEE-WHEEL TESTS AND POWEE
TABLES.
and
the rouet
volante,
w e r e placed o n vertical shafts. The classification by position of
shaft thus served very
we l l
to
distinguish
between water
w h e e l s
and turbines
until tur
bines
were placed o n horizontal shafts. The rouet volante o r flutter wheel
o f the
ancients
consisted o f flat, vertical
vanes
projecting radially
from
a vertical wooden shaft. The
water
jet
from the
feeding spout struck the vanes tangentially near their
ends.
Such
w h e e l s have
been
used
for
centuries in
India,
Egypt, Syria, and southern France. An
excellent example o f a rouet
volante
was
in
use
until
recently
in a plaster mill in western
New York. The
rouet
volante
placed o n a horizontal shaft becomes
essentially the hurdy-
gurdy
o f the early western miners. It
may
thus be considered a s the prototype o f the
modern
impulse
water
w h e e l a s
wel l
a s o f
the
turbine.
M u c h uncertainty o f meaning has arisen from the conflicting u s e o f terms in
classify
ing water w h e e l s . The terms impulse and
reaction,
for example, have been used
by dif
ferent authors
with
opposite meanings.
The
conception
o f
reaction
i s somewhat
difficult
to grasp,
and
a s the definition o f
this
word s e e m s
uncertain
its u s e is to be discouraged.
Its
usual
meaning
wi l l
be
explained, however,
in the
course
o f
this
paper,
in order
that
its
u s e
in
works
o f
reference
may
be
understood.
VERTICAL, \VATERWHEELS
The
overshot
w h e e l i s
a
characteristic type,
although it
is
probably
antedated
historic
ally
by
the
bamboo varia,
which w a s
used by the Chinese,
a s they
claim,
a s
early
as
1 0 0 0
B . C.
A form
o f inverted
chain pump has been used in the Orient from time imme
morial for lifting
water from streams to
irrigation ditches. A
motor
o f
this type
has
recently been patented in America, and o n e is in operation in
Mannsville,
N . Y.,
under
a
head
o f
2 3 feet, yielding abundant power to drive a
grist
and planing mill. Such wheels,
a s
wel l a s
overshot
w h e e l s ,
operate
purely
by
gravity,
and yield theoretically
a
very high
e f f i c i e n c y . The objections to this type o f motor are cumbersomeness, waste o f water by
leakage and spilling
from the
buckets,
inability
to
operate
in backwater,
and obstruction
by i c e in
winter.
Overshot w h e e l s w e r e formerly built
o f great
s ize . O n e at Laxey,
Isle
o f Man, con
structed about
forty years a g o and said
to
be still
in
operation, is 7 2
feet G
inches
in
diam
eter and
develops
about 150
horsepower.o
A number
o f
overshot wheels
are
in u s e at
old mills in
the
Catskill
Mountains
in New York. A firm in
Pennsylvania manufactures
"steel overshot"
water
w h e e l s , which,
it
is
claimed, have
a
high
e f f i c i e n c y .
Breast w h e e l s
a r e
operated
partly
by
gravity
and partly by kinetic energy, the water
from
the
feeding
chutes striking
the floats
or
vanes
o f
the
w h e e l .
Undershot
water w h e e l s
and current wheels operate entirely by the kinetic
energy o f
the moving water.
Tide w h e e l s
and
undershot w h e e l s
usually require
a
floating
framework or other device
to
raise
and lower them with fluctuation in
water
l e v e l .
Breast and undershot w h e e l s never attain high e f f i c i e n c y , and in addition are subject
to
al l
the
objections
o f
the
overshot
water w h e e l . The
labors o f James
Smeaton,
Fair-
barn, and
the
ingenious Poncclet, w h o substituted epicycloidal-curved vanes for straight
buckets in w h e e l s
o f
these types, increased their e f f i c i e n c y somewhat, but such wheels
w e r e
quickly superseded
by
the parallel-flow
turbine o f Jonval and
the
Boyden-Fourneyron
turbines
upon
their introduction into this countiy.
Vertical water
wheels
are
still
con
siderably
used in Germany.
The
theory
o f
water
wheels
has
been
elaborately developed and their literature
is
much
more profuse than that o f turbines, b
a
Se e catologue
o f the Pelton Water W h e e l
Company
for 1898, pp. 70-71.
6 See bibliography o n p a g e s
126-130.
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PRINCIPAL
TYPES
O F
WATER WHEELS. 9
CLASSES
OF
TURBINES.
A turbine a may
be d e f i n e d as
a water w h e e l
in
w h i c h t h e water
is
admitted to all the v a n e s
o r buck e t s s i m u l t a n e o u s l y .
It
is thus
d i s t i n g u i s h e d f r o m vertical
water w h e e l s ,
w h i c h
r e c e i v e
the
water
at the
top
o r
o n e
s i d e o n l y , a n d f ro m i m p u l s e water w h e e l s , w h i c h r e c e i v e a
spout
i n g
jet
o r
jets
f r o m
n ozz l e s
directed
tangentially
a g a i n s t
the perimeter
o f
the
w h e e l .
The
component parts o f
a
turbine a r e the
"runner,"
the "case," the "gate" o r "gates,"
and
the "guides." Commonly the
gates and
guides are included in the "case." The
runner
is
that portion o f the turbine
which revolves.
It
comprises
the vanes,
the crown
plate, parti
tion
plates o r rim
bands, which cover, subdivide, or
strengthen the vanes, and the
power
shaft. The term '' bucket" i s applied to the passage for the water in the runner. The vanes
or floats are
the partitions
separating the
buckets and
forming
the runner.
The
term
"buckets"
i s a l s o often used to signify
the
vanes.
The chutes are the
openings
through
w h i c h the
water
passes into
the
w h e e l ,
and
the guides are the partitions separating
the chutes
The gates
serve
to shut o f f and regulate
the supply.
The
f l o w
o f
water through a turbine
may
be directed either radially inward or outward o r
parallel to
the
axis, or
inward
and parallel, or inward, parallel,
and outward.
The repre
sentative typos o f these several c l a s s e s are a s f o l l o w s :
Tangential f l ow:
Barker's
mil l .
Parallel
f l ow: Jonval
turbine.
Radial outward
f l ow: Fourneyron turbine.
Radial inward
f l ow: Thompson vortex
turbine;
Francis turbine.
Inward and
downward
f l ow:
Central discharge
s c r o l l
w h e e l s
and earlier American type
o f
wheels; Swain turbine.
Inward, downward, and outward f l ow: The American
type o f
turbine.
TANGENTIAL
O U T WA R D - F LO W TURBINES BARKER S MILL.
In
i m pu l s e water w he e l s the jet
s t r ikes
o r
enters
t h e
buck e t s
in a d i r e c t i o n tangential
to
t h e c i r c u m f e r e n c e
o f
t h e
runner. In
m o s t f o r m s
o f
turbines the water
f lows
outward,
inward
o r
d o w n w a r d
t h r o u g h
t h e
b u c ke t s ,
l e a v i n g them
tangentially o r
nearly so .
The
simplest
type o f
tangential
outflow
i s
Barker's
mill, invented in 1740. This w h e e l has
radial
arms and operates purely
by
reaction. Such w h e e l s are still used o n the Morris Canal
in
New Jersey
for drawing
barges
up the
inclined planes
which
serve
in
place
o f
l ocks .
The
w h e e l s have four arms o f 6 feet radius, with
openings
at the ends 3 ^
inches
wide by 15J
inches
h i g h . f r
James
Whitelaw,
o f
Paisley,
developed Barker's
mill,
which
has
spiral tapering
arms
so
curved that water f l o w s radially when the mill
i s
running at proper speed. A w h e e l
o f
this
type
erected
o n
Chard Canal,
1 8 4 2 ,
for purposes
o f hauling
boats
up
inclines developed 7 5
per cent e f f i c i e n c y o n 2 5 feet fa l l . Owing to their large s ize ,
l o w speed,
and inability to
operate in backwater such w h e e l s
have
never c o m e into extensive u s e .
RADIAL OUTWARD-FLOW TURBINES THE FOURNEYRON TURBINE.
A
p r i m i t i v e
type
o f
water
w h e e l , w h i c h c o m e s
under
t h e c la ss o f
turbines
proper is
that
o f
C a d i a t . T h i s is a n o u t w a r d - d i s c h a r g e turbine without g u i d e chutes,
and
t h e r e f o r e it may be
s a i d to
b e l o n g
to t h e
s a m e
s t a g e
in
turbine
evolution
a s d o
t h e
tub
and
s c ro l l
central-dis
c h a r g e w h e e l s , although the
f o r m
o f
runner
and
t h e
d i r e c t i o n o f
f low a r e s imi l a r to
t h o s e
o f
t h e
Fourneyron
turbine. T h e w e i g h t
o f
the runner is
c a r r i e d
by a
step-bearing
at the l o w er
e n d
o f t h e
s h a f t . T h e
d i s c h a r g e
is
r e g u l a t e d
by
a n o u t s i d e cylinder gate, probably the f i rs t
o n e u s e d . T h e
buckets
a r e c u r v e d i n a v e r t i c a l
p l a n e .
F ig .
1
s h o w s a sketch in
s e c t i o n
o f a n e a r l y Fourneyron turbine (after Mo r i n ) .
T h e
g u i d e
chamber
C r e c e i v e d t h e vertical p r e s s u r e
o f water, and
w a s
s u s p e n d e d
f r o m a b o v e by m e a n s
a From Latin
turbo,
to
revolve. The etymology
of the
word
does
not sufficiently distinguish
tho
class.
6
W i l s o n , H . M.,
T h e
Mo r r is C an a l
a n d
i t s i nc l i ne d
p lanes : Scient i f i c
A m e r i c a n
S u p p l e m e n t ,
F e b r u a r y
2 4 , 1 8 8 3
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1 0
T U R B I N E
W A T E R - W H E E L
T E S T S A H D P O W E R T A B L E S .
o f a h o l l o w
c o l u m n surrounding
the
d r i v i n g
shaft. T h e d i sc h a r g e w as
regulated
by a cy l i n
d e r gate
G b e t w e e n
the g u i d e C and the bucket
F.
Sl i t s in the gate
r i n g 6
o p p o s i t e the
e n d o f
e a c h g u i d e e n a b l e d
the
g u i d e s
to
be extended outward
nearly to the
v a n e s .
Fig . 2
s h o w s a p l a n
o f
the g u i d e chamber
and
runner
o f
this turbine. T h e v a n e s o r
buck e t s h a v e
a radial d i r e c t i o n at their
inner
e n d s , w h e r e
they
r e c e i v e the wa t e r .
Under
the
m e c h a n i c a l c o n d i t i o n s e s t a b l i s h e d
the
water
enters
the w h e e l
with
a tangential v e l o c i t y
PIG. 1. Section o f
the Pourneyron
turbine.
e q u a l t o the
v e l o c i t y
o f
the
bucket,
is
c a r r i e d
outward by
the
radial c o m p o n e n t o f its v e l o c i t y ,
and
in p a s s i n g
outward
is
d e f l e c t e d by the backward-curved v a n e s o r buckets, thus d o i n g
work. Inasmuch a s
the
tangential
c o m p o n e n t o f the v e l o c i t y e q u a l s
that
o f the
buckets
the
water
c o u l d
d o n o
w o r k
by
i m p u l s e , h e n c e
the
Fourneyron
turbine
is
purely
a
p r e s s u r e
o r
reaction turbine.
FIG. 2. Plan o f
the Fourneyron turbine.
T h e e x c e l l e n c e
o f
its m e c h a n i c a l
construction,
its h i g h e f f i c i e n c y ,
its
ability
to
w o r k under
very great h e a d s ,
a n d
its ability
to operate in backwater
with g o o d e f f i c i e n c y
r e n d e r e d
the
appearance
o f
the
Fourneyron turbine a
notable
e v e n t in
the
history o f
water p ow e r .
T h e
experiments o f M. Fourneyron w e re b e g u n
in
1823 ,
a n d h i s
f i rs t turbine w a s
e r e c t e d
at Pont
sur 1 ' O g n o n , France,
in 1827. It
w a s f o l l o w e d
by
s e v e r a l o t h e r s , operating under
various
h e a d s
up
to
144
fee t ,
w h i c h
y i e l d e d
ef f i c i enc i es a s
h i g h
a s 80
per
c e n t .
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CLASSES OF TURBINES.
11
In 1 8 3 7 M .
Fourneyron
erected
a
turbine at
St.
Blaise, Switzerland, which
operated under
a head o f 3 5 4
feet. The
diameter
o f
the
w h e e l w a s 1 3 inches. The depth
o f
the buckets w a s
slightly
l e s s than one-fourth o f an inch. This w h e e l made from 2 , 2 0 0 to 2 , 3 0 0
revolutions
per minute, and
is
reported to
have
yielded
an
e f f i c i e n c y
o f 8 0
to 8 5 per cent. The water
w a s
conducted
to
the
turbine through
a cast-iron
pipe
conduit, and
to
prevent
the
chok
ing o f
the
minute apertures in
the
water w h e e l
the supply
was filtered before u s e .
January
1 , 1 8 4 3 , a Fourneyron turbine,
designed
by Elwood
Morris,
w h o had translated
the valuable experiments o f M o r i n
into
English, was erected at Rockland Cotton
Mil l s ,
o n
the
Brandywine. This turbine w a s
tested by
M o r r i s in
the
fall o f
1 8 4 3 , together
with a second
one,
located at Dupont Powder Mill , a l s o o n
the
Brandywine, near Wilmington, Del .
These
turbines gave maximum
e f f i c i e n c i e s
o f 7 0 to 7 5 per
cent,
respectively.
In
1 8 4 4
a Fourneyron
turbine, constructed by Uriah
A. Boyden,
was erected at
the
Apple-
ton
Company's
cotton mills in
Lowell
M a s s . Carefully conducted tests showed that this
turbine yielded an e f f i c i e n c y
o f
7 8 per
cent.
The
Appleton
turbine
w a s
rap
idly f o l l o w e d by others o f
Boy
den's
design, which s o o n became
the
stand
ard
in New
England, displacing the
o l d
wooden vertical w h e e l s .
The
Boyden
turbines w e r e expensive,
cumbersome,
and
gave l o w
e f f i c i e n c y
when
operated
at part gate,
and "owing
to the large
number
o f
buckets
with small apertures
they w e r e liable to b e c o m e
choked
by
chips, leaves,
and other
floating
obstruc
tions,
not to
speak
of f i s h .
At Fall
River, Mass.
the
first
turbines
are
said
to have been
stopped by e e l s
on their
annual migrations to the sea . "a
The
manufacture o f Fourneyron tur
bines w a s
taken up by a
number o f ma
chine works,
and
several
o f the Boyden
turbines are still in
u s e
in New England.
A s usually constructed
this turbine has
a
cast-iron casing
attached
to
o n e s i d e
o f
the
flume, similar to the s c r o l l central-
discharge
w h e e l .
FIG. 3. Section o f
penstock and
runners o f double
Fourneyron
turbine
at Niagara Falls. A, Flume;
B, penstock; CC, runners; DD, guides; EE, buckets;
FF,
gate rings; HH, holes in
upper
drum; //, holes
in lower runner; . 7 " , gate stems.
The
ability o f a turbine
o f
the
Four
neyron type to work efficiently under
very
high heads was shown
by the experi
ments made at
St.
Blaise.
The
manu
facture
o f turbines
o f the Fourneyron type has been revived in recent
years,
owing
to the
demand for
turbines to operate under
very high heads, as at
Niagara Falls and
elsewhere.
Figure 3 shows a schematic c r o s s section
o f
the
double
Fourneyron
turbine
used in the
first
installation
o f
the Niagara Falls
Power Company. This
was
operated under a
head
o f
about 1 3 5 feet.
The turbine i s
mounted
in
a g l o b e
penstock,
similar to that
used in
early
New England practice, with the exception that
two
w h e e l s are used, o n e being placed at the
top
and the
other at
the bottom o f
the penstock.
A s
shown in fig.
3 the runner
C
and
buckets
E,
which
are represented
in black,
are attached to the vertical
shaft. The
guides D
and
buckets E
are
subdivided
into three
compartments
by partition plates. The discharge
is
regulated by
outside cylinder
gates F.
The gate rings for
the upper and
lower wheels are
connected by rods, o n e o f
which i s shown
at J.
The
gate rings F are raised and lowered in
unison to shut o f f the outflow from or to open, o n e
after
another, the
horizontal compart
ments,
as required. The cylindrical penstock is shown in
section
by hachure. The disk or
" W e b be r ,
T h e D e v e l o p m e n t
o f
W a t e r P o w e r .
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Bucket
ring
32
buckets
Guide ring
6 chutes
12
TURBINE
WATER-WHEEL
TESTS
AND
POWER
TABLES.
drum forming
the
lower end o f
the
penstock
i s made solid,
and h o l e s II are provided in the
lower
runner
to a l l o w any water which may enter between
the
lower drum G
and
the l o w e r
runner through
the
clearance
spaces
to pass
out. Holes
HH are provided in
the
upper
pen
stock drum to a l l o w water under full pressure o f the head to pass through and act vertically
against the
upper
runner
C.
In
this
way
the vertical
pressure
o f
the
great
column
o f
water
i s
neutralized and a means
i s
provided to counterbalance
the weight
o f the
long
vertical
shaft and
the
armature o f
the
dynamo at its upper
end. These
turbines discharge 4 3 0
second-feet,
make 2.50 revolutions per
minute, and a r e
rated
at 5 , 000
horsepower.
A section
o f
o n e
o f
the
guide
rings and runners
i s shown
in
f ig .
4. The
guides
and buckets
a r e o f
bronze, and
their
surface curves
form
arcs o f circles
o f
varying
radii.
Except
for the central
thickening
o f the
vanes, the
forms
o f the chutes and buckets
d o
not
differ
materially
from
those
o f
the same parts o f
the
early turbines o f
Boyden and
Fourneyron.
A
Fourneyron
turbine
similar
to
that
at Niagara Falls
has
been
erected at
Trenton
Falls, N . Y .
This turbine
operates
under 2 6 5
feet g r o s s
head
and has 3 7
Fin. 4. Section o f
g u ide s
a n d b u c k e t s ,
F o u r n e y r o n t u r b i n e , buckets,
each
5
inches deep
N i a g a r a Falls.
and
^ ; }
inch
w i d e
at
the least
section.
The total area o f oat-
f l ow at
the
minimum section i s , therefore,
1 6 5
square inches. How enough water can
pass
through
so small
an aggregate aperture to
yield
continuously 9.50 horsepower
i s
a
matter for legitimate wonder.
PARALLEL DOWNWARD-FLOW TURBINE THE JONVAL TURBINE,
The idea o f a parallel-flow t u r b ine ,
is said
to
have originated
with
Euler.
M .
Fontaine put
it
into form
for
practical
u s e ,
and M. Jonval
added
the draft tube from which
it bears
his
name.
In
1 S 3 7
O .
Henschel,
of Oas s e l ,
invented the
downward
parallel-flow
turbine, later
known
bv the
name o f
Jonval
or Koechlin.
T h e
Jonval
turbine closely resembles a later type
o f
flutter
w h e e l known a s
the Borda turbine,
which
has inclined
floats and receives water
from
a
spout directed downward. The
outer ends o f the vanes
are inclosed
in
a
circular
curb.
Thus a runner
o f
the
Jonval
type w a s derived
by
easy
transitions
from the
primitive
flutter w h e e l .
This
w h e e l
receives water
at
only o n e
point
o n
its circumference.
In
the
Jonval w h e e l the spout
i s
replaced by
a
ring o f
guide
chutes, which admit water a l l around
instead
o f
at o n e point. The Jonval w h e e l became
at
once
the
competitor o f
the
Fourney
ron turbine. The
Jonval turbine w a s
introduced
into
America by Elwood Morris and
Emile
Geyelin, o f
Philadelphia,
about the
middle o f the nineteenth century.
The
tub
w h e e l w a s
a
parallel-flow
turbine
without
guides.
This
w a s
placed
in
the bottom
o f
a f l u m e
and commonly contained
a
number o f inclined
or curved vanes,
the
runner
being
similar to that o f the Borda
turbine
in its earlier and to the
Jonval
turbine in its
later
form.
Sometimes
but o n e o r two vanes were used, forming a helix o r s c r e w w h e e l . The tub w h e e l ,
when fitted with a
cover
containing guide
passages
to direct the currents
o f
water against
vanes, becomes essentially a
Jonval
turbine.
The
tub w h e e l w a s in common use in America
at the
time
the Jonval turbine
w a s
introduced.
The theory o f the design o f the Jonval turbine
forms
a neat problem in
applied
mathemat
i c s , and
i s extensively
discussed by
various
writers.^
"
S e e
bibliography,
pp.
120-130.
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CLASSES OF T U B B H S T E S .
13
A variation
o f
the Jonval turbine, in
which
the number o f buckets w a s
reduced
to two,
was
extensively
used
in
sawmills in
northern
New York. Owing to
the
large openings o f the
buckets, i c e ,
drift,
and
other
obstructions could pass through this
w h e e l
without injuring
it.
The
vanes were nearly horizontal, giving a high
speed
o f
rotation.
The e f f i c i e n c y w a s
very
l o w .
In
the Jonval turbine the velocity o f water
at
the outer ends
o f
the buckets
i s
greater than
that at the inner ends. In order to increase
the capacity
o f the w h e e l without the l o s s o f
power
that
would result from unequal velocities in
the
outer
and
inner portions o f a
broad
FIG. 5. Section
o f
Francis
center-vent
turbine at Booth
Cotton Mi l l s , 1849.
C,
Guide
chutes:
D,
run
ner; < ? , inside cylinder gate ring;
H,
holes
through
runner disk to
admit water and neutralize
pres
sure:
.R,
gate stems.
bucket
annulus,
the
Geyelin Double
Jonval turbine
has
been devised.
This
contains
two
rings o f
buckets,
o n e
within
the other, the
inclinations
o f
the
buckets differing, so
that the
angular velocity o f both
rings
i s
the same;
the intention being to secure a turbine o f large
capacity
in small compass.
Jonval
turbines are still
manufactured by
a number o f American firms, and
rating tables
are
given
o n pages
98-100.
RADIAL INWARD-FLOW TURBINES THE FRANCIS TURBINE.
James B .
Francis,
w h o was
intimately
associated witli Uriah
A .
Boyden in testing
early
American Fourneyron turbines, experimented
in
1 8 4 7 o n a
model o f
a
center-vent
turbine
which was
essentially
a
Fourney
ron turbine having the relative
positions
o f the
guides
and buckets
and
the direction
o f f l o w re versed,
a
Such a w h e e l
had
been proposed
by
Poncelet
in 1826. A patent
w a s issued to
Samuel
B . Howd,
o f Geneva,
N.
Y.,
in 1 8 3 6 for an
inward-flow turbine, s o m e features
o f which w e r e embodied in t h e .
Guide chutes
FIG.
6. Section
o f runner o f
Francis center-vent
turbine.
Francis turbine.
The
inward-flow
turbine
was
destined to
supplant
a l l others,
but it
w a s soon found best
to
extend
the buckets downward,
thus
making an inward
and
downward f l o w turbine.
MIXED-FLOW
TURBINES.
This
c l a s s
includes (A) scroll
central-discharge w h e e l s , embracing
(1)
turbines without
guides,
(2) the Burdin turbines, (3) Thompson
vortex
turbine; (B) early American types
o f turbines
having
double-curved
buckets
extended downward b e l o w the guide ring, but not
protruding outward.
In these w h e e l s
the runner can
be
lifted
vertically
out o f the
c a s e .
o Francis, J.
B v
Lowell Hydraulic
Experiments, pp.
55-60.
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1 4
TURBINE
WATER-WHEEL
TESTS AND
POWER TABLES.
FIG.
7. Schiele
turbine.
SCROLL
CENTRAL-DISCHARGE WHEELS.
S c r o l l - c a s e
turbines have flat
vanes, or
vanes
that are curved
but little
from a
vertical
plane.
The action
o f the
water is chiefly
radially inward, although the
discharge is
both
upward and
downward.
The
best developed
turbine
o f
the
s c r o l l
central-discharge type
is
the
Schiele
which
has
curved guide
vanes
and
buckets,
the latter
attached
to periphery
o f a
central
drum.
( S e e
f ig.
7.) The discharge is controlled by a gate
in the chute.
The Thompson
vortex turbine and certain
American types
o f bulging-bucket
turbines
mounted
in
scroll cases
also'discharge
both
up
ward and downward. Many scroll central-dis
charge turbines,
with
no guide passages
and with
the controlling gate
in
the throat o f the s c r o l l
case, are still in use.
The
gate
is
either
o f
the
sliding or
o f the pivoted butterfly
type. Some
forms o f
this
w h e e l
have rudimentary guide
pas
sages,
two in
number,
opening on
opposite
sides
o f
the
runner, their object being to
distribute the
water
equally
around the periphery
o f
the wheel, and to prevent
a
portion o f the runner
from "running
dry.'
AMERICAN TYPE
OF
TURBINES.
The
earliest step toward
the
development o f
the turbine in America is a
patent
issued to
Benjamin
Tyler,
o f
Lebanon,
N.
H.,
in
1 8 0 4 ,
signed
by
Thomas
Jefferson,for
an
"improve
ment in watei
wheels."
Apparently the
water wheel
improved
i s
a
primitive flutter w h e e l
or
rouet volante, and
the
improvement consisted in hoop
ing
the
w h e e l with iron hoops
and setting the wooden
vanes at a
specified
angle.
Credit for
the
s c r o l l c a s e i s assigned by W. W. Tyler
to
the Parker brothers, o f
Licking
County,
Ohio, the
American
patentees o f the
draft tube
in the early half
o f
last
century.a
From 1 850
to
1 8 7 5 many turbines
w e r e
built nearly
o n
the
lines
o f
the
Howd-Francis
turbine, but with
buckets curved downward to an increasing extent in
successive forms.
Tests
o f
the
Swain wheel in
the
six
ties proved conclusively
the
merit o f this type.
In
the
same decade the pivot o r wicket gate a s successfully
applied
in the "American"
and
"Leffel"
turbines,
and
thus a step in advance was taken toward improvement o f the part-gate
e f f i c i e n c y
o f
turbines. LefTel a l s o introduced
the
short
draft
tube, carrying the bridge tree
and step
bearing,
giving
the
turbine
c a s e practically
the
form at
present retained.
The Risdon
turbine having an inside cylinder gate and buckets slightly curved downward led in
e f f i c i e n c y
at
the tests
made
at
the Centennial
Exposition
o f
1 87 6.
At
this
exposition
much attention w a s a l s o
attracted
by tests
o f
the Little Giant turbine, manufactured by
Knowlton
& Dolan,
o f
Indianapolis,
under
a patent issued to Matthew
and John
Oben-
chain.
This w h e e l has
ladle-shaped bulging buckets, and similar
w h e e l s were
soon
devised
by John
B .
M c C o r m i c k , from w h o s e
designs
the
Hercules,
Hunt,
Victor, and several makes
o f ''McCormick" turbines have
been developed.
In figure
8 the arrows indicate the inward and
downward
direction
o f
f l o w
o f
the
water.
Provision is made
for
a slight outward f low. In
turbines
o f this type, a s
we l l
a s in
those
FIG. 8. Cross
section
of an early
turbine with deep, bulging buck
ets,
pivot
gates,
and
an
adjustable
bearing (B).
a
Tyler,
W.
W.,
Evolution o f the
American Type
o f Water Wheel.
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U.
S.
GEOLOGICAL SURVEY
WATER-SUPPLY
PAPER NO. 180
PL. I
A.
RECENT AMERICAN TYPE OF WATER-WHEEL RUNNER.
B.
DYNAMOMETER, HOLYOKE TESTING FLUME.
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CLASSES OF TUEBINES. 15
with
inward
and downward
f l o w only, the
buckets
are
commonly
made
o f
wrought iron
or
steel secured
in a
cast-iron head,
a s
here shown, and strengthened by
a
band at C .
C l e m e n s Herschel writes:a
American
turbines
are
mostly o f a
complex
nature, as regards the action o f the water
on
the buckets
o f the wheels, and
have
been perfected in efficiencyby test, or,as it is irreverently called, by the " cut and
try "
method
o f procedure. A wheel would be built on the inspiration o f the inventor,
then
tested in
a
testing flume,
changed
in
a certain part,
and retested, until no further
change
in that
particular could
ef f ec t
an improvement.
Another part
would
then
undergo the same process o f reaching perfection,
and
thus in course o f t i m ' e the whole wheel would
be brought
up to
the
desired high standard o f e f f l c i e n c y .
The
American type o f turbine
i s
distinguished by the great depth
o f
its buckets, its great
capacity in proportion to
its
diameter,
and
by
its
high speed. It
i s
a l s o distinguished
by
the
form o f its
buckets,
which
consist
o f a
ring
o f
curved vanes
arranged parallel to
the
axis and
inclosed within
the guide
ring.
Below
the
guide ring
the
buckets expand down
ward and
outward, forming large
cup-shaped outlets.
The evolution
o f turbines having enormous capacity compared with their
s i ze i s
largely
the
result
o f
the
desire for
great
power
in
a small
and consequently
cheap
wheel,
and
the
desire
to
procure as high a speed a s possible. The speed o f a w h e e l under a given head
varies
inversely a s its
diameter.
T o increase the capacity o f
a
turbine without increasing
its diameter requires an increase in its depth. Thus w h e e l s with
very
deep buckets have
been evolved. This
i s illustrated
in
PI .
I,
A,
showing
the inlet end
o f
the runner
o f a deep-
bucket
w h e e l .
When a w h e e l
i s
operating under l o w
heads
the lower part
o f
a deep bucket i s operating
under
an
appreciably greater
head
than the upper
part;
hence to maintain a proper velocity
o f
the
water
passing
through
the turbine,
and to enable it to
leave
the runner with a l o w
velocity, large
bucket
outlets
are
required. These could
not
be obtained in
the narrow
compass
o f a
runner
o f
small
diameter, and to remedy this
defect large
cup-shaped buckets
protruding
downward and
outward
from
the
inlet chutes were devised. The
course
o f
the
water
in passing through
these
complex
buckets
is
first radially inward, then axially
down
ward, then tangential, o r
outward
o r both, thus
effecting
a nearly
or
quite
perfect
rever
s i o n o f current direction. The large ladle-shaped vents perform
another
important func
tion in
that
they
distribute
the water uniformly within the draft tube.
Recent improvements in
this
form
o f
w h e e l have been (1)
the
arranging o f w h e e l s in
pairs o n horizontal
shafts,
made possible
by the use
o f
the draft tube;
(2)
the
invention o f a
governor that wil l control
the
speed
o f the
w h e e l
with a
degree o f uniformity
that
is
com
parable with that effected by the best engine regulators; (3)
the
development o f such a
relation
between
the gate
mechanism
and
the runner
design as
to
give a
high
e f f i c i e n c y
with
a considerable range o f gate
opening.
American turbine practice differs from
European
practice in that
water
wheels are
placed
on
the market in
standard or stock
s izes , whereas
in
Europe, notably o n the Continent,
each turbine i s designed for
the
special conditions under
which it
i s to operate, the designs
being
based
on mathematical
theory and
following chiefly the Jonval and
Fourneyron types.
Thirty
years
ago there w e r e probably
more
establishments engaged in the
manufacture
o f
turbines than there are to-day. The
keen
competition o f that time led to the development
o f better turbines,
and the
relatively small
number
o f firms
having
the
ingenuity
and the
facilities to
meet
the demand are the o n e s that have survived. At the
present
time a large
majority
o f
the turbines
used
in
this country
are
built
in
half
a dozen
factories.
Having
been developed
by
experiment
after
successive
Holyoke tests
(described o n
pp.
36-37), American
stock
pattern turbines probably
give
their best
e f f i c i e n c i e s
at about the
head
under which those
tests
are
made i.
e., 14 to 1 7 feet. The shafts, runners, and cases
are so
constructed a s
to
enable
stock s izes
o f
wheels to be
used
under
heads
ranging
from
6
to 6 0 feet. For very
l o w
heads they are
perhaps
unnecessarily cumbersome. For heads
exceeding 6 0 feet American
builders
commonly resort to the use o f bronze buckets and
"special
wheels,"
not designed along theoretical
lines, a s in Europe,
but
representing modi
fications o f the standard patterns.
oCassier's
Magazine,
Niagara
power
number, July,
1895,
p.
243.
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16 TURBINE
WATER-WHEEL
TESTS AND
POWER
TABLES.
TYPES OF TURBINE GATES AND GUIDES.
Practice as
to chutes
or guides differs widely. They are
usually
fewer in number than
the
buckets.
The cogent dogma
o f
water-wheel
design
i s that
the
water
should
enter without
shock
and
leave
without
velocity. This implies
that the direction
o f
motion
o f
water
on
leaving the buckets
shall
be
opposite
to that o f the buckets
themselves,
and that its velocity
relative to the buckets shall
be
equal to that o f the buckets. The water wi l l then have no
velocity
relative
to
the earth.
This law requires that
the
water shall
enter the
buckets at
an angle at
which
it wil l
glide smoothly
in
without
shock.
The
guide
passages are made
as
f e w in number a s is reasonably
consistent
with this dictum.
The
constmction
o f
turbines
without guides has
a l s o
its advocates.a
With regard both to
the
e f f i c i e n c y and
the
general
merit
of
the wheel, the gates are per
haps
the
most important feature. Among the different
types o f
gates are outside register
gates,
inside register gates, inside cylinder
gates,
wicket o r
pivot
gates.
Register gates may
be
o f the plate o r o f
the
ring type, according
as
they are applied to
parallel-flow or
inward-flow
turbines. In
each
class o f
turbines register gates are
some
times used outside and sometimes
inside o f
the
guide chutes.
Outside
register
gates, adapted to the
Jonval
type
o f
wheels and to
plain
inward-flow
tur
bines,
w e r e named from
their
similarity
to
a common
hot-air register.
Such wheels
are
o f
small
capacity in proportion to their weight and diameter. Obstructions readily catch in
the gate and
chute
openings
and prevent the gates from being c l o s e d tightly,
and
the down
ward
pressure o f
the
water
o n the register ring makes it
difficult to open.
When the
regis-
teris partially c l o s e d ,
the
usefulness o f the
guide passages
i s in part
nullified
and the result
ing e f f i c i e n c y o f the wheel i s diminished.
The inside
register gate i s
placed
between the chute
ring
and
w h e e l
runner instead
o f
being
outside
o f
both.
It
i s
sometimes applied to
wheels
o f
the
American
type
having inlet pas
s a g e s parallel
to
the
axis
a s we l l a s
to Jonval
w h e e l s , in
which the inlet
passages are in a
plane at right
angles
to the
wheel axis.
Cylinder gates are applied to turbines o f the
Fourneyron
and American
types,
but not to
Jonval turbines.
The cylinder
gate
moves over the
inlet ports
in a
direction parallel to its
axis, cutting o f f
the
supply at the top
o f
the guide passages instead
o f
at the side,
as
does a
register
gate.
The
inside
cylinder
gate i s
the form o f
gate most
commonly
used o n wheels o f
the
Amer
ican type. It consists o f a
cast
ring having a
width
equal to the depth o f the inlet
o f the
buckets, supported
by counterbalance weights and moved
by
gearing. By moving it
up
o r
down
the depth
o f
the inlet
passages
is
increased or diminished
as desired.
It
s
commended
by its
e a s e
o f
operation and
its
freedom
from c l o g g i n g . When it
i s
partially closed the con
traction o f the water in passing
the sharp
metal lip o f
the
gate causes swirls and
eddies to
form
in
the upper
part o f
t h e ,
buckets. The smooth
curved form o f the guiJe passages
is
fully effective
only when
the
w h e e l is running with
the
gate w i d e open. In order to lead the
water smoothly into
the
buckets at al l gate openings, a
set
o f
"false
guides," o r
garnitures,
is
sometimes attached to the
lip
o f the gate cylinder to prevent
the
breaking
or throttling
o f
the
inflowing water, b
Another
device intended to
prevent
inefficient
operation
when
the
buckets
are only par
tially f i l l ed , a s at part gate, consists in
the
u s e
o f
division plates, by which the water
is
entirely shut out
o f
the upper part
o f
the
w h e e l
when
it
i s
operating at
part
gate.
This
makes
the
turbine, in effect, a s e r i e s
o f
water wheels
placed
o n e
above
another.
Such
water
wheels are commonly called double turbines. They may, however, be distinguished from
another style
o f double turbines,
the
Leffe l , in which two essentially different wheels
are
combined and mounted o n
the
same
shaft for the purpose
o f increasing
the
capacity
o f
the
turbine
without
increasing its
diameter.
When
an inside
cylinder gate i s
raised, an open
space
an inch or more wide
i s left
between
the
guide
chutes and buckets.
In
order to
avoid
this and to conduct
the
water
a
Tyler,
W . W . , T h e
evolution o f
the
A m e r i c a n
type
o f
water
w h e e l : Jour.
Western Soc. Eng. vo l .
3 ,
C h i c a g o ,
1898.
&Wet>ber,
S a m u e l , Ef f i c i e nc y
o f
turbines
as
a f f e c t e d
byform
o f
gate: Trans.
Am.
S o c . M e c h . E n g . ,
1 N S 2 .
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18/138
MECHANICAL PRINCIPLES.
17
more
perfectly
to the w h e e l , an outside
cylinder
gate has
been devised,
called a "sleeve
gate," consisting o f a
cylindrical
ring slipping outside
o f
both
runner and
chute ring.
Wicket
or
pivot gates, a s
the
terms are
applied to
the American type
o f
turbines, are a
combination o f gates
and guide passages. The leaves o f
the
guide ring are
so
pivoted o n
their centers
a s
to
balance
and
swing by
levers and
gearing. Their
inner
ends
approach
or
recede from o n e another, increasing
or
cutting o f f the supply to the w h e e l runner a s desired.
A s usually constructed, al l
the
gate leaves move simultaneously: a modification consists in
a
series o f
hinged gates,
which
c l o s e
o n e
after another
a s it i s
desired to
decrease
the
power.
When a gate
i s
opened
at
all,
it
is
opened full width, and
the
number o f fractional gate
open
ings at which
the
wheel can
operate
is
determined by the
number o f gates.
Pivot
or
wicket gates are conducive to
high
part-gate e f f i c i e n c y provided they are so
con
structed a s
not
to change the
"entrance
angle " o f
the
water a s it strikes the buckets at part
gate.
Cylinder-gate turbines
may
be
so
designed a s to
yield their maximum e f f i c i e n c y
when
running at about
three-fourths
gate, the depth
o f
buckets
being
so great that
the
discharge
i s
"choked"
and
s o m e e f f i c i e n c y lost
at
full
gate.
In
this
way a good e f f i c i e n c y scale for
part
gate i s
obtained
with cylinder-gate turbines.
Pivot gates
contain
many parts and
are a s a rule more liable to
obstruction,
leakage,
and breakage
than
cylinder
gates. They are, however, extensively
used with
very satisfactory
results.
MECHANICAL
PRINCIPLES
OF THE TURBINE.
N o
attempt
wil l
be
made
to
enter
into the mechanical principles
o f the
turbine from a mathematical stand
point, a s the theoretical equations o f
relation are long,
involved, and vo
luminous in
development.
Only a
very general discussion
o f
the subject
wi l l
therefore
be given.
The,
principle o f reaction, a s operat
ing in turbines, i s
illustrated
in f ig. 9.
If
the
w h e e l
W
w e r e
held rigid,
the
water
would
spout
from
the
o r i f i c e s
A,
B,
and
O
with
a
velocity due to the head H. If pistons similar to
P
w e r e
fitted
in the o r i f i c e s , these
pistons
would
bo driven
outward by
the pressure.
If, now,
the
pistons were held rigid, but the
wheel w e r e f r e e
to
revolve,
the pistons
would be forced
outward
a s before
relative to the
wheel,
but the w h e e l must then revolve.
The
water head H exerts a direct pressure o n
the
pistons,
and in accordance
with
Newton's second l a w
o f motion,
an equal and opposite pressure o r
reaction
i s
exerted outward against the back walls M, M, M o f the. arms A, B, and G .
Sim
ilarly,
i f the pistons w e r e removed, and i f the w h e e l w e r e free to revolve,
the
unbalanced
pressure
against the
back o r
outer
walls
M,
M,
M
o f
the
arms would cause it to
revolve and
with a peripheral
velocity
nearly equal to that
"due
to
the
head H.
The
theorem
o f
Torricelli requires
that
the water
shall
issue
from an
o r i f i c e
with
a
velocity
equal
to that acquired by a body falling through a
height equal to
the head.
In the c a s e o f
the
Barker's
mill
the o r i f i c e itself
i s
moving with this velocity
and
in a con
trary direction. Hence the water wil l
have
the required velocity
relative
to
the
w h e e l ,
but
wil l
have n o
velocity
relative to the earth and wi l l
drop
nearly inert
from
the
o r i f i c e s . This
simple phenomenon has been carefully traced
out,
in
order
that its application in the
l e s s
evident
example
o f
a
turbine bucket
may
be made
clear.
IKE 180 06 2
FIG. 9. Diagram
illustrating
the principle o f reaction.
The figure
represents a Barker's
mill o f
the
Whitelaw
type.
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1 8
TURBINE WATER-WHEEL
TESTS
AND
POWER
TABLES.
FIG. 10. Diagram illustrating impulse against curved
vanes.
Let
A, f ig. 10 , represent
a
s i n g l e bucket
in
the vane ring
o f an
outward-discharge turbine,
the
inner
or guide
ring
being
removed. Assuming
the
bucket to be attached to the axis
o f
the
turbine
by
the
radial arm
B,
the similarity
o f
conditions to those shown in fig. 9
is
obvious.
This illustration applies equally
we l l
to either an outward, inward, o r
downward
discharge
turbine,
so
far
a s
reaction
i s
concerned.
Inasmuch
a s
the bucket A
revolves,
the water must enter the bucket, if
at a l l ,
with
a
tangential
velocity equal to the v e l o c
ity o f the bucket and
in
the
same
direction. Guide
chutes
facilitate
the action by
properly directing the
current o f
water in entering
the
bucket,
a s
indicated
at C ' , f ig . 1 0.
Action by
impulse against a mov
ing vane
takes place
a s
f o l l o w s :
First
consider
the
vane
V,
f ig.
1 1 ,
a s stationary. The jet from a guide
chute enters the bucket
in
the
direc
tion
A
B and
leaves
it in the direction
C D,
so that
its direction o f motion is
changed through
the
angle
B E C.
If the water spouting from the
guide
chute
A would
have reached B
at
the
same time that
it
actually
reaches C , then
A
C would represent
the resultant velocity. The l i n e A C
comprises two components (1)
the initial
velocity
A
B and (2) a velocity imparted by the vane V.
From
the parallelogram o f forces w e find
graphically
for
the
latter
the
value B
C.
This force i s exerted a s a
push
against
the vane,
tending to rotate it o n its
axis.
It can d o
work by
causing the vane to
move forward or
to
revolve
against
resistance,
and the amount o f work
done D
wil l
be
represented by a com
ponent
o f the
force B C (modi
f i e d by the motion o f the vane)
parallel to
the
line
o f
motion
and acting
through
the dis
tance v where v i s the
velocity
o f
the
vane i.
e.,
the velocity
o f
rotation
o f
a turbine.
If the vane V w e r e properly
curved and moved with such
velocity relative to
that o f the
jet that the jet left its outer
end with a
backward
velocity
equal to,the forward
velocity o f
the
wheel, then
the
jet
would
FIG. 11. Diagram illustrating t h e o r y o f
m o v i n g v a n e s .
have no velocity relative to the
earth and
would
drop inert, its entire energy having been imparted to the vane.
With
most forms o f gates the s ize o f the jet i s decreased a s the , gate i s closed, the bucket
area remaining unchanged, so
that
the w h e e l
operates mostly by
reaction at full
gate and
by impulse to an
increasing
extent
a s
the gate is c l o s e d .
Hence, the speed
o f maximum
. , n ,
,
. peripheral velocity .
e f f i c i e n c y varies a s the gate i s c l o s e d .
1
he ratio , -, , V lormaximumernciency
for
a
36-inch Hercules turbine
i s
given in
the subjoined
table.
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20/138
MECHANICAL PKDSTCIPLES.
Velocity
a t
various gate openings
for a 36-inch
Hercules
cylinder-gate
turbine.
1 9
Proportional
gate
opening.
Full.
0.806
.647
.489
.379
Maximum
e f f i c i e n c y .
Per
cent.
&o.60
87. 1
86.3
S O
73.1
Peripheral
velocity.
Velocity
duo
head.
0.677
.648
.641
.603
.58.5
Centrifugal
f o r c e
a l s o plays an important part
in
turbine
action.
The complete theory
o f the turbine, including consideration o f friction and centrifugal
f o r c e ,
involves intricate
mathematical
analysis. The
principal
results to which it leads are a s follows:
Given
the head and
quantity
o f
water and
speed
required, theory indicates
the
diameter
o f w h e e l and
the
initial
and
terminal angles o f the
vanes.
It d o e s not determine the. form o f
the vanes,
the curved
surfaces o f which are
usually
made
up o f circular
arcs for simple
inward-,
outward-,
and downward-flow turbines. Neither
is
the number
or
the depth o f the
buckets determined, except that their normal sections shall be such a s to give
the
water tho
required
velocities in passing
through.
Theory d o e s not indicate
the
numbers o f
guides or
buckets
most
desirable. If, however,
they
are too f e w , the
stream
wil l not properly
f o l l o w
the f l o w lines indicated by theory. If
the buckets
are too small
and
too numerous,
the surface-friction factor wi l l
be
large.
It
i s
customary to make
the
number o f guide chutes
greater
than
the
number
o f
buckets,
so
that
any object
passing
through
the
chutes
wil l be
likely
to'pass through the
buckets
a l s o .
In
a
Jonval turbine the guide ring and bucket ring have equal radii. In
the
Francis,
Thomson,
and
American
types
the
radius o f
the guide
ring
is larger, requiring oftentimes the
thickening o f the
guide
partitions
in order to give
the
water
the proper initial velocity
where
it enters the
buckets.
HORSEPOWER AND
EFFICIENCY
OF
TURBINES.
The
energy
or
capacity
for doing
work-resulting from a weight W falling through a height
H
is
Energy in
foot-pounds=Tf H.
A hoisepower was defined by
James
Watt a s
the capacity
to perform work at
the
rate o f
3 3 , 0 0 0
foot-pounds o f
energy
expended per minute.
If the weight o f a
cubic foot o f
water
i s w >
and
the f l o w
o f a stream
is Q cubic feet
per
minute, then the theoretical horsepower wil l be
WE =QwE
33,000~33,000
Takingw, the weight o f water,
at 6 2 . 4
pounds per cubic
foot,
the factors for obtaining the
theoretical horsepower are the following:
0.1135XffXcubic
feet
per
second.
0.001S9x#Xcubic feet per minute.
0.000253X-0XU. S . gallons
per
minute.
0.3643X-0XU.
S.
gallons
per 2 4
hours.
0.00227X#XCalifornia
miner's
inches
(=0.02
second-foot).
0.00295X#XColorado
miner's inches (=0.026 second-foot).
0.0007S9v/2gX#
L'XF (vent in square inches).
0.00632X.EPXF
(vent in square inches).
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2 0
TURBINE WATER-WHEEL TESTS
AND
POWER TABLES.
The horsepower
o f
a stream decreases about one-fourth
o f
1 per cent
with
a variation
of
the temperature o f
the
water from 40 to 75 F.
For
precise calculations
the exact
weight
o f pure water
may be useful.
Weight
and dimensions ofdistilled
water
a t stated temperatures.
[ W e i g h t
in
p o u n d s . ]
Tempera
ture,
de
grees Fah
renheit.
32
39.3
50
60
70
80
Relative
density.
0.
99987
1 .
00000
.99975
.
99907
.99802
. 99669
Weight
per cubic
foot.
62. 416
6 2 . 4 2 4
6 2 . 4 0 8
62. 366
6 2 . 300
62. 21 7
Weight
per cubic
inch.
0. 0361
.0361
.0361
.0361
.
03607
. 03602
Weight of
column 1
inch
square,
1
foot high.
0. 4334
. 4 3 3 5
. 4 3 3 3
. 4 3 3 0
. 4 3 2 6
. 4 3 2 0
Weight
per
U. S .
gallon.
8 . 345
8.
3 4 5 4
8. 3 4 3 3
8 . 3 3 83
8. 3295
8 . 3 1 84
Cubic
feet
per
ton.
32.
04 3
3 2 . 0 3 9
32. 04 7
3 2 . 0 6 9
32.
103
32. 145
Weight
per
cubic yard.
1 ,
685.
2 3 2
1,685.448
1 , 684.
908
1,683.882
1 ,
682. 100
1 , 679.
85 9
a Smith, Hamilton, Hydraulics.
b
Maximum density.
In
practice
the theoretical power
i s always
to be multiplied
by
an e f f i c i e n c y
factor
E to
obtain
the net power
available on
the turbine shaft a s determinable by dynamometrical test.
Manufacturers' rating tables are based o n e f f i c i e n c i e s usually between 7 5 and 8 5 per
cent.
In
selecting
turbines
from
a maker's
list
it i s often important to
know the rated e f f i c i e n c y .
This may be obtained by the following
formula
E==
tabled
e f f i c i e n c y .
H. P.= abled horsepower, and
Q=tabled discharge (C.
F.
M.)
for
any head H.
u,_ 33.000XH.P. _ _ _
H.P.
The
tabled
e f f i c i e n c i e s
for a number o f styles and s i z e s o f
turbines
are
shown
in the
accom
panying table.
Rated
efficiency of
water
wheels.
F r o m m a n u f a c t u r e r s ' power tables . ]
Name
of
wheel.
Do........................................................
Do........................................................
Do........................................................
Do........................................................
Do........................................................
Do........................................................
Do........................................................
Diameter
in
inches.
2 4
4 8
4 5
4 8
2 4
4 8
24
4 8
2 2
4 4
2 5
4 8
2 4
4 8
Percentage
of efficiency
at 10-foot
head.
81. 52 0
8 0. 8 00
80 . 7 5 4
79. 877
7 9 . 86 9
80.004
79.
94 5
80.000
79.
93 7
8 0. 110
8 0. 010
7 9 . 8 3 0
7 9 . 90 5
7 9 . 91 4
7 9 . 9 1 4
Percentage
o f e f f i c ie n c y
at 4 0 - f o o t
head.
79.856
79 856
80.800
79.
94 4
79. 93 1
79.
91 3
79.
907
79 . 9 06
79 . 9 07
79. 841
8 0. 126
79.890
79. 776
79. 936
79 . 9 33
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HORSEPOWER A W D
EFFICIENCY.
21
The
e f f i c i e n c y at
which
wheels are rated by the builders varies slightly with the s ize o f
the
w h e e l , a s we l l a s
with
the head,
in
many
c a s e s .
Owing to
the
different
weights o f
water
assumed,
etc.,
the
e f f i c i e n c i e s
o f wheels intended to be rated
at
80 per
cent differ
slightly
from that amount where computed from the
manufacturer's
power
tables.
Prior to the
classical
experiments o f
James B . Francis on the
f l o w o f water
over w e i r s in
1 8 5 2 at the.
lower
locks in
Lowell
the diversity o f formulas used for
calculating
f l o w through
turbines makes the results o f
early
tests incomparable o n e with another, and the accuracy
o f
s o m e
later experiments
preceding the building
o f the present
Holyoke testing f l u m e is s o m e
what
in
doubt.
It can
hardly
be said that there has been a progressive growth in the e f f i c i e n c y
o f tur
bines, a s the
following
outline
o f the results o f successive
series
o f tests
wil l show:
In 1 7 5 9 James Smeaton reported tests o f 2 7 undershot water w h e e l s showing
e f f i c i e n c i e s
varying
from
2 8 to
3 2
per cent. Similar tests
o f
1 6 overshot wheels showed e f f i c i e n c i e s
varying from 7 6 to 9 4 per cent.^
In
1 8 3 7 M . M o r i n
tested
several Fourneyron turbines. O n e at St. Blaise
showed
an effi
ciency o f 8 5
per cent under
3 5 4
feet
head.
For
another,
under
a lower fa l l , 88 per cent effi
ciency
is
claimed, b
In 1 8 4 3 Elwood Morris introduced and tested Fourneyron turbines in the United States.
Turbines
in
Rockland
mills
and
Dupont
powder
mills,
Wilmington,
Del. , showed
7 0 and 7 5
per
cent
maximum e f f i c i e n c y , respectively.
In 1 8 4 4 Uriah A . Boyden
built
at Lowell the first Fourneyron turbine used in New Eng
land,
which showed
o n
completion
an e f f i c i e n c y
o f 7 8
per cent, c It i s claimed
that
s o m e o f
Boyden's later turbines
showed
an e f f i c i e n c y , o n
test,
o f 8 8 to 9 2 per cent.
In
18 59
and 1 8 6 0
competitive tests o f
1 9 wheels at
Fairmount
Park waterworks showed
e f f i c i e n c i e s a s
f o l l o w s :
Results of tests of turbines a t Fairmount Park, Philadelphia, Pa., in 1859 60.
Efficiency.
Number of
turbines.
1
0
2
Efficiency.
Number
of
turbines.
4
3
2
1
In 1 8 7 6
C e n t e n n i a l tests s h o w e d maximum
e f f i c ienc ie s
a s f o l l ow s
f o r
17 w h e e l s :
Results of ests
of
turbines a t Centennial Exposition, a t Philadelphia, in
1876.
Efficiency.
Number of
turbines.
3
4
Efficiency.
Number of
turbines.
5
4
1
The large
majority
o ' f
turbines
sold at the
present time are made
at
the shops o f f i v e
o r
six
builders whose wheels have been
frequently
tested.
The
average full-gate e f f i c i e n c y
shown in
recent
Holyoke tests
o f
standard patterns i s
c l o s e
to 80
per
cent.
S o m e early
wheels showed
very
high e f f i c i e n c i e s ,
but prior to the
building o f
the
Holyoke
flume the large majority w e r e o f low e f f i c i e n c i e s .
o Evans, Oliver, Millwright's Guide,
Philadelphia,
1853 , pp. 131-154 .
6 Journal Franklin
Institute,
October to December,
1813.
c Francis, J. B., Lowell Hydraulic Experiments.
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22 TURBINE WATEK-WHEEL TESTS
AND
POWER TABLES.
During the past thirty years the
'general
standard
o f
e f f i c i e n c y o f turbines has been
steadily raised, although the maximum attained may
not
exceed that
o f
some
early
forms.
The uniformity o f
each maker's
wheels, a s we l l as
their strength