V PAP-448

HYDRAULICS BRANCH OFFICIAL FILE COPY

BUREAU OF RECLAMATION HYDRAULICS BRANCH

OFFICE FILE COPY When Borro~1ed Return Prompt 7 y

HYDRAULIC CHARACTERISTICS

OF AN EMERGENCY CYLINDER

GATE CLOSURE

BY

BRENT W. MEFFORD

PAP-4,48

HYDRAULIC CHARACTERISTICS OF AN

EMERGENCY CYLINDER GATE CLOSURE

by

B. W. Mefford

.µ Enclosure -- -

-· CONTENTS

Glossary .

Background of prototype tests

Objectives of current emergency closure studies

Math model

Tower boundary conditions

Downstream boundary conditions .

Hydraulic downpull ..

Results ...... . Tower water surface . Hydraulic downpu11 forces

Comments on forcing functions

Bibliography

i

Page

iii

l

2

3

3

4

5

6 7 8

10

11

.r

Figure

l

2

3

4

5

6

7

8

9

10

11

12

13

14

15

FIGURES

Unmodified lower gate ...

1950 prototype test results

1953 prototype test results

Physical layout for math model

Cylinder gate coefficient of discharge

Needle valve coefficient of discharge

Upper gate Hr vs. percent of gate

Lower gate Hr vs. percent of gate

Both gates Hr vs. percent of gate

Minimum predicted hydraulic downpull on upper gate

Maximum predicted hydraulic downpull on upper gate

Hydraulic downpull on lower gate

Minumum predicted hydraulic downpull on upper gate -dual-gate operation . . . . . . . . ....

Maximum predicted hydraulic downpull on upper gate -dual-gate operation . . . . . . ..

Hydraulic downpull on lower gate - dual-gate operation . . . . . . . . . . . .

i i

12

13

14

15

16

17

18

19

20

2l

22

23

24

25

26

GLOSSARY

a = wave speed (ft/sl

AC = area of cylinder gate (ft2l

AN = area of needle valve (ft2}

Ap = area of penstock (.ft2}

AT = area of tower (ft2)

Coe= coefficient of discharge through cylinder gates

c0N = coefficient of discharge through needle valves

CM = nesia~ive charactc;·i~tic

Cp = positive characteristic (.ft)

dH = increment of head (ft)

dt = increment of time (t)

g = acceleration . of gravity .. (ft/s?)

HE = elevation head of .needle valves (_ft}

HN · =needle Valve head(.ft}

Hp = head at beginning of penstock (ft)

HR = reservoir elevation head (ft)

HT = tower water elevation head (ft)

N = number of needle valves open

QC = discharge through cylinder gate (ft3/s)

QN = discharge through needle valves (ft3/s)

Op = discharge through penstock (ft3/s)

QT = discharge through intake tower (ft3/s)

i ii

-~ .. -

,.

HYDRAULIC CHARACTERISTICS OF AN H1ERGErJCY CYLINDER GATE CLOSURE

Background of Prototype Tests

In 1950 and 1953 prototype tests were conducted at Hoover Dam to detenni.ne

if the intake tower cyl"inder gates could be closed with a differential

head across the gates. The tests were designed to measure the hydraulic

downpull force on the lower cylinder gate at fixed positions over a range

of differential heads across the gate. Tests were not conducted on the

upper cylinder gate.

The 1950 tests were conducted on the original ~y-linder·:gate (fig. 1). The .

bottom lip of the gate and the gate seat formed a shallow diverging nozzle

downstream from the point of control. When a cavitation vapor cloud forms

downstream from the control point, part or all of the gate bottom can be

subjected to vapor pressure. For the tests, vertical gate openings of 3, 5,

6, 9, and 15 inches were tested under a reservoir elevation of 1168 ft.

The tests were conducted by (1) establishing a fixed gate opening without

flow, /C2} controlling the penstock discharge by staging the opening of

the downstream needle valves, and (3) recording tower water surface and -~ hydraulic downpull at set intervals. A maximum hydraulic downpull force

of 540 kips was measured during the tests. Tl1e maximum force occurred at

the ~-in gate opening (fig. 2). Although the downpull forces measured during

the tests were not felt to be excessive, all tests were halted with the

tower water surface at about 1020. The tests were stopped due to observations

of noise and vibration in the tower.

Based on the results of the 1950 tests, the bottom edge of the lower gates

v1ere modified to reduce hydraulic downpull forces during emerg_ency closure

-,;. .... -

(fig. 3). Hydraulic downpull tests were conducted on the modified lower

cylinder gate in 1953. The same test procedure was used as in 1950. Fixed

gate openings of 3, 5~ 9, and 12 inches were tested under a reservoir

elevation of 1155 ft. A maximum hydraulic downpull of 130 kips at a 3-in

gate opening was measured during the tests.

Noise and vibration present during the testing were considered substantially

less than encountered during the unmodified gate tests.

surface was allowed to drop to about elevation 940 ft.

The tower water

Tests were halted

at that point due to turbulence in the tower water surface endangering

test equipment.

Objectives of Current Emergency Closure Studies

A hydraulic analysis of an emergency closure of the cylinder gates was

conducted to:

l. Predict the tower water surface elevation in response to emergency

closure of the cylinder gates

2. Estimate hydraulic downpull on the gates under actual closure

conditions

3. Determine how hydraulic downpull varies with the mode 6f operation

4. Identify possible hydraulic forcing functions capable of exciting

the gate structure

2

Math Model

A math model of the hydraulics of the inlet tower, penstock, and needle

valves was developed to partially meet the above-listed objectives. Pen­

stock . laterals and turbines were omitted. The model was developed for

both single- and double-gate operation.

Previous mathemati.cal studies conducted by Ball JJ and physical model studies

conducted b.y Col gate' y_ poi:nted to fl ow condi.ttons. under the _-·gate at sma 11

openings exhibiting cavitation, and flow separation which could not be

handled in detail. Although assumptions about the flow conditions under

the gate must be made, where possible, assimilation of prior prototype

data was used to define the boundary conditions of the model. The math

model was developed as a transient model based on the method of character­

istics. The intake tower, penstock, and outlets were sectioned as shown

on figure 4. Above elevation 893 ft the intake tower was treated as a

single boundary condition. The penstock was then broken into three 600-ft­

lo_ng segments for transient computation. The downstream boundary condition

was defined by four 72-in needle valves discharging free.

Tower Boundary Conditions

The upstream boundary condition was defined by the following equations:

1. Flow through the cylinder gate,

1/ Ball, J. W., Unpublished USBR Hoover Dam file No . 225, Book l, 1955. y Colgate, M., Unpubl'ished USBR Hoover Dam file No . 225, Book l, 1955 .

')

2. Flow in the tower,

(neglect friction)

3. Flow into penstock,

4. Definition of the change in the tower water surface,

5. Compatibility equation at the boundary,

H_ p = CM + aQp ~ p

All unknowns can be found by simultaneous solution of the five boundary

equations at time T. By expreising the equations in finite difference

form using a second order approximation, the boundary equations can be

solved at time T + dt . Prototype data avilable from the 1953 tests l/

were used to estimate: the coefficient of discharge through the cylinder

gates at small openings. The same coefficient of discharge equations

were used for both gates (fig. 5).

Downstream Boundary Conditions

The downstream boundary was defined by the simultaneous solution of two

equations:

l / Unpublished USBR Data Book, Hoover Dam file No. 225, Book 2, 1955.

4

1. Flow through the needle valve,

2. Compatibility equation at boundary,

There are no calibration curves available for the 72-in needle valves.

An equation for the coefficient of discharge, figure 6, was developed

from information on the 84-in Hoover needle valves in conjunction with

1953 prototype test data.

Hydraulic Downpull

Hydraulic downpull on the gates was calculated using pressures at the

center of the gate opening. Hydraulic downpull was defined as the unbalanced

force created by the difference between tower hydrostatic pressure . and the

calculated pressure profile, each acting on the horizontal area of the gate.

For th_e upper gate configuration, pressures were calculated at five locations

inward on a radial line on the bottom of the gate leaf. The area between

adjacent calculated pressure points was assumed to be acted on by a force

equal to the average of the pressure times the area.

Insufficient prototype data are avail ab le to clearly define the gate loading

due to cavitation or flow separation occurring along the gate bottom. Both

conditions can affect the prototype hydraulic dovmpull forces under sub­

merged conditions. The pressure di stribution during cavitating conditions

presents the greate~t infl uence on hydraulic downpull forces .

-.... _

Studies done by Colgate ..l/ have shown the formation of a vapor cloud near

the leading edge of the bottom results in a distorted pressure distribution

over the downstream gate area. To bracket the pressure distribution on the

upper gate, two separate cases were studied in the numeric model:

1. Assume cavitation does not distort the downstream pressure distri­

bution.

2. Assume if cavitation forms at a point on the bottom of the gate, the

entire downstream portion of the gate is subjected to vapor pressure.

During free discharge the gate was considered to be aerated. Minimum pressures

under the gate were restricted to atmospheric pressure.

Cavitation has less influence on the lower cylinder gate. The modification

to the lower gate forces the high-velocity jet to separate sharply from the

gate bottom. The area of the pressure distribution affected by a vapor

pressure cloud is significantly reduced. The pressure distribution on the

lower gate was modeled by treating cavitation as a point source. Pressures

.downstream of the point of separation were calculated based on a linear

pressure recovery up to hydrostatic conditions in the tower.

RESULTS

Simulated emergency gate closures were based on reservoir elevation 1210.0 ft.

All emergency closures simulated by the model were based on a constant rate

of cylinder gate closure. A total gate stroke of 9. 17 ft in 12.33 minutes

6

was adopted. Steady-state conditions based on the initial discharge through

the penstock were modeled before emergency closure of the cylinder gates

v1as started.

Three cases of emergency cylinder gate closures were modeled. Both the

upper and lower gates were modeled separately and during combined operation.

Tower vJater Surface

Figures 7 through 9 show the dependence of tower water surface elevation on

cylinder gate opening for upper, lower, and simultaneous dual-gate operation.

The discharges shown represent steady-state penstock flow established by the

discharge capacity of the needle valves at the beginning of the tests.

Case 1. - Upper gate closure with lower cylinder gage closed (fig. 7):

The upper cylinder gate remains submerged during full closure for initial

discharges up to about 4000 ft3/s. Severe cavitation on the gate is

not predicted in this region of operation. At higher discharges a cavi­

tation cloud is expected to occur on the bottom of the gate as the tower

water elevation falls below 1075.0 ft. The tower water surface within

t~e cavitating zone is falling at between 1.5 and 3.0 ft/s over the range

of discharges shown. The rate of drawdown in the tower water surface

limits the existence of .severe cavitation on the gate to a period of

10.0 to 20.0 seconds.

7

Case 2. - Lower cylinder gate closure with upper cylinder gate closed (fig. 8):

The lower cylinder gate remains submerged during full closure for initial

discharges up to 6000 ft3/s. Fully developed cavitation is expected to

occur for gate openings of less than 1.0 ft under differential heads

of greater than 250 ft.

Case 3. - Simultaneous dual closure of both the upper and lower gates (fig. 9):

Operation of both gates produces rapid drawdown of the tower water surface

over the .final foot of cylinder gate closure. Both gates can be closed

under submerged conditions for initial discharges less than 4000 ft3/s.

The lower tower gate remai~s submerged for flows up to 6000 ft3/s. Strong

cavitation occurs on the gates in zones similar to those identified for

single-gate operation. Strong cavitation is expected to occur on the

upper gate for a period of 5 to 10 seconds before the jet breaks free.

Hydraulic Downpull Forces

-Case 1. - Upper cylinder gate closure with lower cylinder gate closed (figs. 10

and 11}:

Figure 10 shows the predicted hydraulic downpull under the assumption

of point cavitation. The gate operates under a nearly constant hydraulic

downpull until the tower water surface starts falling r~pidly. After

the jet breaks free, hydraulic uplift on the gate can occur.

8

-...~-

Hydraulic downpull forces, assuming cavitation subjects the entire down­

stream portion of the gate to vapor pressure, are shown on figure 11.

Within the cavitation zone, large increases in the hydraulic downpull

forces occur. A maximum hydraulic downpull of 375 kips occurs for initial

discharge of 6100 ft3/s at a 0.43-ft gate opening.

Case 2. - Lower cylinder gate closure with the upper cylinder gate closed

(fig. 12) :

The treatment of pressure recovery and cavitation on the modified gate

produces smaller downpull forces than obtained for the upper gate. Highest

hydraulic downpull forces act on the gate at gate openings of less than

1.0 ft. Maximum hydraulic downpull forces predicted fall under 300 kips.

Case 3. - Simultaneous dual closure of both the upper and lower cylinder

gates (_f i.gs. 13-15}:

Figures 13 and 14 show the hydraulic downpull forces acting on the upper

cylinder gate during emergency closure of both upper and lower gates.

Downpull forces given on figure 13 were formulated assuming cavitation

does not distort the pressure distribution under the gate. In contrast,

hydraulic downpull forces calculated assuming a full cavitation vapor

cloud under the gate are shown on figure 14. Similar to upper gate

operation alone, large spikes arise in the downpull force during operation

in the cavitation zone. Again, due to rapid tower water surface drawdown,

the large forces exist for short periods of time.

The range of predicted downpull forces on the lower gate during emergency

dual-gate closure are shown on figure 15. The progressive · buildup and

sharp decay of forces are similar to single-gate operation, but of lower

magnitude.

COMMENTS ON FORCING FUNCTIONS

Steady closure of the cylinder gates used in the model does not produce

transient pressures capable of exciting the gate. A review of literature

and analysis of flow characteristics under the gate failed to identify a

hydraulic forcing function capable of producing a sustained periodic

transfer of energy between the flow and gate. Cavi t ation and separation

on the ~ate can act as extraneous excitation, yielding damped aperiodic

vibrations. Significant random tower vibration and turbulence within the

tower water are expected as the tower water level approaches the level of

the gates.

10

--

BIBLIOGRAPHY

[l] Falvey, H. T., Air-\.Jater Flow in Hydraulic Structures, USBR Engineering Monograph 41, 1980.

[2] Martin~ H. M., and J. W. Ball, Laboratory and Prototype Tests for the Investigation and Correction. of Excessive Downpull Forces of Large Cylinder Gates under High Heads, Sixth Congress IAHR, Delft, Netherlands, 1955.

[3] Naudascher, E., Engineering for Structures Subject to Flow-induced Forces and Vibrations, Manuscript, University of Karlsruhe, Karlsruhe, Germany, 1980.

[4] Rouse, H. Selected Writings, Paper - Jet Diffusion and Cavitation, p. 529, 1971.

[5] Schlicting, H., Boundary Layer Theory, McGraw Hill, 1968.

[6] Staats, B. H., J. H. Ball, and M. C. Henery, USBR field trip report,. Downpull Tests on Hoover Dam Intake Tower Cylinder Gates, August 1950.

[7] USBR unpublished data file No. 225, Hydraulic Downpull on Hoover Intake Tower Cylinder Gates, 1950-53.

[8] Wylie, B. E., and V. L. Streeter, Fluid Transients, McGraw Hill, 1978.

11

i

·.·-· . . ·~ .·:.; ·.·.· ..

•' -+--- ------- ---t»;EH---+- -~-l----- ~

<O

\ ,,-Stems and brackets furnished

:' ;iy the qovernment

HALF PLAN

I

DD oo· DD DD oo· ool

Fi gure 1. - Unmodified lower gate. 12

SECTIONAL PLAN

. ?

•. . ·<-. . I> . .

:'

- ---+--- ------l.-+-1+- ~ --~ ------+!IJ-#hil-l---'?

19

:o:: ·.··:;":_;.:.·>:·:·.?>···:.. . . <:'.'.· : :: o_::-., .. :·<=a:.·:_.

. . . . . ~. ·_·_ o·_.·: -..

:·.·.·o .

~----- ------- -'"-· - ---- ll'-0 11-------------- -- -J ~·:·.·. 9

SECTION A -A X'::i : ·o .

::.:; • Q·

Slope !=60-·'·

·L,·. . • 0

. . . (2

~-· .. <) · . . J

. : •;J::···· . . . . .. a . ·q ':)

... .

c:, 0 O")

'

.. . .· :C) . .

0 ••

n . . :: c::j .. . . J. = . .. Q .•

. . . . ·. ·. Q.

· . · · : · .. : .J . · .. :~·.· .·.· .. ·.J:. . (>

LIST OF DRAW/1' FOP. LOWER GATE

DETAIL ASSEMBLY-UPPER AND LOWER GATE!

ITEM I

LOWER £~TRANCE AND INTERMEDIATE LINER

BULKHEAD GATE SEATS-SILL-BOLTS-LIST OF PA

ITEM 2 LOWER GATE THROAT LINER AND LIST OF PAR'.

LOWER NOSE LINER .......... .. .. .. .

LOWER CYLINDER GATE ............. .

GATE SEAT-DEFLECTO!?----GUIDE SHOE ...

GUIDE BAR SUPPORTS AND SPACER RING ..

GUIDE aARS-SEATS-BOLTS ..

NOTE: ~ ~ For stress-strain diagram For def. o0 yield strength see Dw9 L/5-D-22f.

~

·~{ :~>>.

O• .•. ·• ·.::::.)·. •. ~.·.

· o .:::.;> .• ·<J: .Y.·c:. ·.,_··.

DE:PARTMENT o ·F THE. INTER/1 BUREAU OF R£CLAMATl01'

SOULOER CANYON PRO.JI

BOULDER DAN INTAKE TOWERS

32!.o" 0/A. CYLINDER , GENE;.R.AL ASSEMBLY-LO

ORAWN ____ .W,.11:.~ , . ... SL1BM1TT£O ... .. Cd}. 'U{_ T.RACE'D... J . J. $ . . .. REC0MM£ND£D .. .. • .,,.

CHECKEO . . ~.: ... ·.·.· . ... APPROVED ........ .': . .f:.•

'2458'2. DENVER . COLO., OEC -~4.(932. SHEET 2 OF' IS

1180

116 0

1140

1120

I-w 1100 LI.I LL. .

z 1080

z 0 -I-

1060 <t > LI.I .....J

· W 1040

w u ~ LL.· 1020 a:: ::, C.f)

a:: 1000 w ~ ~

:= 980

0: l.:J

:= 960 0 I-

940

920

900

880

I I I I I ,-Reservoir wa t er surface El.1155.0

I , 1 , • ,

~--'.L '- .....

j ~ ' ..._-

~ -/

~ ~ ,, ~x ~

,,

i ~~~,~~ /(,Cu_tting FLOW \ > ~~ I! line

V

I

\' \ ~~ ,, ~~ ~11

J }i 0 I

t----~~-~---~ ~,-Portion_ \ ~~ \

r ~/ , , "" , ' .,

C '""-5" ";~ ____ ,;\i>,~jj · removed

I' _\ 0\ I

\ A·. - GATE BOTTOM

x"- ~ MODI Fl CATION

a\ ~

~ ,. I ~I

~ . 9" '-. ~,- x, ~

\ - -~ r',.x ~

~' ~ \ ,..,

~ . --~ 'x \ '"-12 I

"'- . X

~ ) 0 V . ~, J o/

l,£ / 2 ~' 0 ~x---- I

-3"Gote opening /;~ I I

yx/Y/

I I . I I

I I ..

,- Got e s e o t E 1. es 3. 5 o ' ' ' ----r l

! -40 - 20 0 20 40 60 80 100 120 140 160 180

HYDRAULIC DOWN PULL IN KIPS

8. - HY DR A U L I C DOWN PU L L ON MO DI F I ED GA T E

- GATE MODIFICATIONS AND Fl ELD MEASUREMENTS OF HYDRAULIC DOWN PULL FORCES - MODIFIED LOWER

CYLINDER GATE - HOOVER DAM INTAKE TOWER

) (1163 Fi gu re f. -~ pro t ot./p e test resu lts .

--- Reservoir water surface El. 1168.0 I I 6 0 r--_ f..~, ...;..:..;:,I .:.;_;_:I ~, :...:...=..:.,.,.::.:_:;:-~, _ ~--,-, ~-

~ I- I I 6 0 1..------+-I --+-I --"-I ___:____:l-----l--1 ......J--.-+----,-1 --l--L...___J

~ ~ I I 4 0 ~~~~-+,--+--!....I -~-+-+--+,--+--!---I · C:: LI.. I I 2 0 ~~~...!-..:~---!-----J.._-L--l---J.-....!....._.!....-.......;.....---1

~ ~ _ I I O O ~...._.a..__:.,..!.....:~----:..::=..;;;,...,;._I ~-L-----l---1----1-----1-___ '-!---l wZ I- 0 c::r - IO 6 0 ~.......;.....--l-~-.:::.;....,,---+--~~~~--+--+---+---1

3:: ~ C:: > IO 6 0 1-----!--4-----,.__,.,~-+----+--...p,..~..__~,._~ wW 3:: ..J I 04 0 ~---+---+----!-.....+L~-r---+-+:--+__;:...+-~~...+----l e w 1s"Gote opening)

I O 2 0 l----1--4-----,.

1

--.--+-----1--....---1---1.---,L;......_--1---i

I O O O L---+--...:..____. _ _.__.__--4-_...:..___..__-i...._1...----!----J

0 100 200 300 400 500 600 HYDRAULIC DOWNPULL IN KIPS

A. - HY DR AU LI C DOWN PU LL FOR R ECO R DE D GATE OPE N I N GS

11 BO

:; 1160

Lu LI.. 1140

z 11 20

z 0

11 00 I-~ > 1080 w ~ 1060

w u 1040 ~ LL. cc: ::, r.f>

cc:

1020

1000

W 980 I-~

:;: 960

C: W 940 :;: 0 I- 920

900

. ,-- Reservoir water surface El. 1168.0

~-i-1 I I ~ I ~ I I ~ i"'-,... ___

I I ~ ~ ...._,

~t'--~I I ,~ .........

"' f'-......!"-....

"'- -.. "'-~ I

.........

~ " ""'"' ~ "- " I I 1,

\I '~9" 3~ 4'!)_ ' -· ,

I I T l/ I I I I I I

I- I I I I I ~

/ ,/ / ,,, / 1,../

12"Ga'te openi'ng-f ,,. ~/ /j / ------, I I I t '. 1 l/ ,..;/_,,,,

I I I

I j/' ~>71/,..-

I --1 I ,-.,..-~(

I I I )7 ;/~-

I I I I I Q

/ I ,,-<""r

I )/::vi' I I I I 0 100 200 300 400 500 600

HYDRAULIC DOWN PULL IN KIPS

B. - HYDRAULIC DOWN PULL FOR GATE OPENINGS ADJUSTED FOR STEM ELONGATION

FIELD MEASUREMENTS-HYDRAULIC DOWNPULL FORCES-LOWER CYLINDER GATE-HOOVER DAM INTAKE TOWER

2, lct5 0 Fi ;ure f . -~ prototype test results.

1 /I

__ , U1

HR = I 2 I 0. 0 ft.

-TOWER WATER SURFACE

UPPER GATE

EL. 104 5.0 ft

LOWER GATE EL. 893.5 ft.

UPSTREAM BOUNDARY CONDITION

¢=1

600 ft. SECT I ON l-

,,__~~~~~7~2---i-n._N_E~E~DL-E~VA~L,VES) 600 ft. SECT I ON

1 ·

[ ., _ ___,,l Q'--~~ EL.652.9 f t. HPl,3_~., 0 L HP2,2_6f

C:s ft. i-d PENSTOCK

Figure 4. - Physical layout for math model.

i , !

1. 000 t I !

0.500

I

~ I r I

i

r I i I

o I,

-o 0.100

u f t

0. 050 l--1

r I

I-

I ! i I I

I

HOOVER CYLINDER GATE COEFFICIENT

d. /

I /

I /

/

/ //

/ ; '

I /

// I

/ /

6 Y = 0. 0088 X 1. 0009 <0. 0! .. 4. 5!)

6 Y = 0. 0103 X 0, 8996 (4. 5% .. 11. 0%)

6 Y = 8. G070 X 1. 05S3 (i 1. 0! .. ie0. 0%)

a010 L< _____ ,_,_ __ L . . L J . . Lu ~--L _____ . , ___ __ , ... ,. __ L.L. LLLl

1 5 10 50 133

PERCENT CYLINDER GATE OPENING

Figure 5. - Cylinder gate coefficient of discharge.

16

HOOVER DAM 72 - in. NEEDLE VALVES

I I

I

I I

I

I I

I

.6. Y = K. 8180 X 0. 9392 '1. 0% .. HJD

.6. Y"' S.~ X 0.94S2 (101 .. 701)

.6. y = B. 86Z4 X B. 4714 C7B% .. um>

0.. 810 ..__ _ _..__-.J-~~.._.._......,,..'t:--_....__~~~J....L.LL-' ---'~-~•--J...' ..... , ..... , ..... , ...... ii 0. 1 8. 5 L 0 5. 8 18. 0 58.8 100.. 0

PERCENT OF FULL GATE OPENING

Figure 6. - Needle valve coefficient of discharge.

17

-····-

1250

1200

1150

,..... 1100 .J

4--._;

w u < LL 0:: :::)

1650 (J)

0:: w I-< J=c

0:: w J=c 1000 0 I-

950

900

850 = I.[") = I.[")

is:5 is:5 - -

HOOVER UPPER CYLINDER GATE

o Q Ci) = 15300 CFS o Q(i) = 13500 CFS

FULLY DEVELOPED o Q(i) = 9900 CFS b Q (i) = 6100 CFS

STARTS <> QCi) = 2200 CFS

'ELEVATION OF GATE SEAT 1045. 0 ft.

= I.[") = I.[") = I.[") = I.[") = I.[") = I.[") = I.[") = u,

c-J c-J en en ...; ...; Ln Ln c.o c.o r-: r-: co co en en GATE OPENING (ft.)

Figure 7. - Upper gate Hr vs. percent of gate. 18

= is:5 -

1250

1200

1150

""' 1100 .J 4-~

w u < LJ.. 0:: :::)

1050 Cf)

0:: w I-< ::3:

0:: w ::3: 1000 0 I-

950

900

J, I

= IJ"")

csS csS

HOOVER LOWER CYLINDER GATE

o C (i) = 15300 CFS o C(i) = 13500 CFS o C (i) = 9900 CFS A C(i) = 6100 CFS <> C(i) = 2200 CFS

FULLY DEVELOPED ~CAVITATION

STARTS

I I I I = IJ"") - -

~ ELEVATI~ OF GATE SEAT 893. 5 ft.

I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I = IJ"") = u, = IJ"") = Lr) = Ln = Ln = Ln = Ln = N N en en ...;. ...;. i.rS i.rS c:c5 c:c5 i:-! i:-! co co cl cl ;;9

GATE OPENING (ft.)

Figure 8. - Lower gate Hr vs. percent of gate.

19

-.. .... _

-.J 4-..._,

w Ll < LL.. er: ::::, (.J)

er: w f-< :3:

er: w :3: C) f-

HOOVER CYLINDER GATES

12ml

1150

TOTAL DISCHARGE 1100 o Q (i) = 15300 CFS

o Q (i) = 13500 CFS FULLY DEVELOPED o Q(i) = 9900 CFS

CAVITATION ( STARTS ON UPPER GATE '6. Q Ci) = 6100 CFS

1050 EL 1045

1000

FULLY DEVELOPED 950 ~CAVITATION

STARTS ON LO~ER GATE

000 1 EL 893.5 ft.

= i.n = i.n = i.n = Lr') = Lr') = Ln = Ln = Lr') = Ln = Ln = CQ CQ ..... ..... N N c-r$ c-r$ ...,; ...,; ~ ~ cd cd r--! r--! co co oS oS CQ

GATE OPENINGS (ft.)

Figure 9. - Both gates H1 vs. percent of gate.

20

.....

- :., . ...-

-Cl> 0.. .... ~ ........

_J _J :::) 0... z :;.:: 0 a u ..... _J :::)

< 0:: a >-:J:

400

250

200

150

100

0

-50

HOOVER UPPER CYLINDER GATE ASSUME POINT CAVITATION ON GATE BOTTOM

o C Ci) = 15300 CFS o C(i) = 13500 CFS o C(i) = 9900 CFS b.. C (i) = 6100 CFS

ts::ILJ"'>ISILJ"'>=LJ"'>ISlLJ"'>=LJ"'>=LJ"'>ISlLJ"'>=LJ"'>ts::ILJ"'>ts::ILJ"'>ISl

cs5 cs5 - - c-J c-J m m ...; ....; in in co cd r--= r--= co co en c:n cs:S

GATE OPENING Cft.) Figure 10. - Minimum predicted hydraulic

dovmpul 1 on upper gate .

21

-

·• ..... -

400

250

,..., 0)

200 I a.. "" .x - ,-.....J

.....J ::::) a.. :z 150 i ::i:: 0 0

u ...... .....J ::::)

100 < n:: 0 >-:::c

50

I I I I I = LJ") . ...... .....

I I = c--J

HOOVER UPPER CYLINDER GATE ASSUME FULL CAVITATION CLOUD ON

GATE BOTTOM

I I I I I I I I I I I I I LJ") = LJ") = LJ") = L(")

c--J en en ~ ~ ~ ~ GATE OPENING

I I I I I = LJ")

cd cd

(ft.)

() C(i) = 15300 CFS o CCi) = 13500 CFS r;J Q Ci) = 9908 CFS .6. Q Ci) = 6100 CFS o Q Ci) = 4200· CFS

I I I I I I I I I = LJ") = LJ") ISi

r-: r-: co co cl

Figure 11. - Maximum predicted hydraulic downpull on upper gate.

??

,. ___

I I I I LI"') = cl ~

,,... (I) CL ....

..x: '--'

_J _J :::, CL z ;3: C) Cl

(.) ...... _J :::, < e::: Cl >-:I:

•

2fill

150

100

50

0

-50

HOOVER LOWER CYLINDER GATE

O O(i) = 15300 CFS o C (i) = 13500 CFS o C (i) = 9900 CFS A Q (i) = 6100 CFS

= U") ISi U") ISi U") ISi U") = U") = U") = I.(") = U") = U") = U") ISi ..d ~ ...... ...... c-J c-J m m ...; ...; iA aA co co c-: i:--! cc a:$ cl cl ~

GATE OPENING (ft.)

Figure 12. - Hydraulic downpull on lov1er ga te.

23

-. ,.-

HOOVER CYLINDER GATES 400 *UPPER GATE FORCES

*POINT CAVITATION iOTAL DISCHARGE

350 O Q Ci) = 15308 CFS

~i o Q{i) = 13688 CFS o C(i) = 0000 CFS I::.. CCi) = 6100 CFS

+ 250f

,..... (I) a.. .... m ~ ........

....J

....J ::::) 0.. z 150 3: C) Cl

t u ...... ....J ::::)

< HID e::: Cl >-:c e 0

53 .,. __ _

El

A 0

J 11! t ,•I -~ Jll -100¥ei I I I I I I I I I I I I I I ! II I I I I I I I I I I I I I I I I I I I I I = LI") = Ln = LI") = Ln "-I U") ISi Ln ISi LO = U"') = U"') 1SI Ln = i:s5 i:s5 . c-J c-J m m ...; ...; Ln Lrl c.d c.d r-.: r-.: o:5 o:5 c:rl c:rl ~ - - -- -GATE OPENING (ft.)

.... Figure 13. - Minimum predicted hydraulic downpull

on upper gate - dual-gate operation.

24

..

..

,,..,, 0) 0... ....

..:i:: .._..

_J _J :::, 0... :z Ji: 0 Cl

u 1-4 _J :::, < 0:: Cl >-::c

150

100

0 I

I 1 -50

HOOVER CYLINDER GATES *UPPER GATE FORCES

*FULL CAVITATION

TOTAL DISCHARGE O Q (i) = 15380 CFS o Q (i) = 1360B CFS o Q (i) = 9908 CFS t:,. Q(i) = 6100 CFS

= I.(") = I.(") = Ln = Ln = Ln ISi Ln = Lt') = Lt') = Lt') = Lt') = ,:s; ,:s; - - c-J c-J m m ..,; ..,; 1..n i.n cd cd c...: c...: c:d c:d oS oS ~

GATE OPENING (ft.)

Figure 14. - Maximum predicted hydraulic downpull on upper gate - dual-gate operation.

2S

·~ .. -

, •

•

-co a.. .....

..I:: ......,

• _J _J ::::) 0.... z 3: C) Cl

u ...... _J ::::)

< er. Cl >-:::r:

400

200

150

100

50

0

-50

HOOVER CYLINDER GATES *LOWER GATE FORCES

TOTAL DISCHARGE o Q Ci) = 15300 CFS o QCi) = 13608 CFS o Q Ci) = 9980 CFS t::. Q Ci) = 6100 CFS

0

El

ISi Ln = Ln ISi Ln = Ln = Ln = L(") = Ln ISi Ln = Ln = Ln = cs:5 cs:5 ~ ~ c-J c-J m m ...; ...; in r..n c.d c.d t-! t-! co co d d ~

GATE OPENING Cft.) Figure 15. - Hydraulic downpull on lower gate -

dual-gate operation.

26