MAP WITH SITE SKETCHED IN.
The following questions cover information which, although not The following questions cover information which, although not necessary in starting to plan a water power site, will usually necessary in starting to plan a water power site, will usually be ne
this will save time later. this will save time later.
1.
1. Give Give the the type, type, power, power, and and speed speed of of the the machinery machinery to to bebe driven
driven and indiand indicatecate whether whether direct, direct, belt, or belt, or gear drigear drive isve is desired or acceptable.
desired or acceptable. 2.
2. For For electric electric current, current, indicate indicate whether whether direct direct current current isis acc
acceptaeptable ble or aor altelternatrnating ing currcurrent ent is ris requiequired.red. Give Give thethe desired voltage, number of phases and frequency.
desired voltage, number of phases and frequency. 3.
3. Say Say whether whether manual manual flow flow regulation regulation can can be be used used (with (with DCDC and very small AC plants) or if regulation by an automatic and very small AC plants) or if regulation by an automatic governor is needed.
governor is needed.
MEASURING GROSS HEAD MEASURING GROSS HEAD Method No. 1 Method No. 1 1 1.. EEqquuiippmmeenntt 42p51.gif (353x353) 42p51.gif (353x353) a.
a. Surveyor's Surveyor's leveling leveling instrument--consists instrument--consists of of a a spiritspirit level fastened parallel to a telescopic sight.
level fastened parallel to a telescopic sight. b.
b. Scale--use Scale--use wooden wooden board board approximately approximately 12 12 ft ft in in length.length. 2
2.. PPrroocceedduurree a.
a. Surveyor's Surveyor's level level on on a a tripod tripod is is placed placed downstream downstream fromfrom the power reservoir dam on which the headwater level is the power reservoir dam on which the headwater level is marked.
b.
b. After After taking taking a a reading, reading, the the level level is is turned turned 180[degrees] 180[degrees] in in aa hori
horizontzontal cial circlercle.. The sThe scalcale is pe is placlaced doed downstwnstream ream from from itit at a suitable distance and a second reading is taken.
at a suitable distance and a second reading is taken. This process is repeated until the tailwater level is This process is repeated until the tailwater level is reached.
reached.
<MEASURING HEAD WITH SURVEYOR'S LEVEL> <MEASURING HEAD WITH SURVEYOR'S LEVEL> 42p52a.gif (437x437)
42p52a.gif (437x437)
M
Meetthhood d NNoo.. 22
This method is fully reliable, but is more tedious than Method This method is fully reliable, but is more tedious than Method No.
No. 1 and 1 and need need only only be usbe used whed when a sen a surveurveyor'yor's levs level is el is notnot available. available. 1 1.. EEqquuiippmmeenntt 42p52.gif (393x393) 42p52.gif (393x393)
a. Scale a. Scale b.
b. Board Board and and wooden wooden plugplug c.
c. Ordinary Ordinary carpenter's carpenter's levellevel 2
2.. PPrroocceedduurree a.
a. Place Place board board horizontally horizontally at at headwater headwater level level and and placeplace leve
level on tl on top of op of it fit for acor accuracurate lete leveliveling.ng. At thAt the dowe downstnstreamream end of the horizontal board, the distance to a
end of the horizontal board, the distance to a
wooden peg set into the ground is measured with a scale. wooden peg set into the ground is measured with a scale. b.
b. The The process process is is repeated repeated step step by by step step until until the the tailwatertailwater level is reached.
level is reached.
<MEASURING HEAD WITH CARPENTER'S LEVEL> <MEASURING HEAD WITH CARPENTER'S LEVEL>
42p53.gif (522x522) 42p53.gif (522x522)
MEASURING FLOW MEASURING FLOW
Flow measurements should take place at the season of lowest Flow measurements should take place at the season of lowest flow
flow in in order order to to guarantee guarantee full full power power at at all all times. times. InvestigateInvestigate the stream's flow history to determine the level of flow at
the stream's flow history to determine the level of flow at bot
both maxh maximum imum and mand miniminimum.um. OftOften plen planneanners ovrs overloerlook thok the face fact that thatt the flow in one stream may be reduced below the minimum level the flow in one stream may be reduced below the minimum level req
requireuired.d. OtheOther strr streams eams or soor sourceurces of pos of power wwer would ould then then offeoffer ar a better solution.
better solution. Method No. 1 Method No. 1
For streams with a capacity of less than one cubic foot per For streams with a capacity of less than one cubic foot per second, build a temporary dam in the stream, or use a "swimming second, build a temporary dam in the stream, or use a "swimming hole"
hole" created created by by a a natural natural dam. dam. Channel Channel the the water water into into a a pipepipe and
and catch catch it it in in a a bucket bucket of of known known capacity. capacity. Determine Determine thethe stream flow by measuring the time it takes to fill the bucket. stream flow by measuring the time it takes to fill the bucket.
Stream flow (cubic ft/sec) = Volume of bucket (cubic ft) Stream flow (cubic ft/sec) = Volume of bucket (cubic ft)
Filling time (seconds) Filling time (seconds) Method No. 2
For streams with a capacity of more than 1 cu ft per second, For streams with a capacity of more than 1 cu ft per second, the
the weir weir method method can can be be used. used. The The weir weir is is made made from from boards,boards, log
logs, os, or scr scrap rap lumlumber.ber. Cut Cut a rea rectactangulngular oar openpening ing in tin thehe cen
center.ter. SeaSeal the l the seamseams of ts of the bohe boards ards and tand the sihe sides bdes built uilt intointo the
the banks banks with with clay clay or or sod sod to to prevent prevent leakage. leakage. Saw Saw the the edges edges ofof the opening on a slant to produce sharp edges on the upstream the opening on a slant to produce sharp edges on the upstream sid
side.e. A sA smalmall pl pond ond is is formformed ed upsupstreatream fm from rom the the weirweir. . WheWhen tn therheree is no l
is no leakage aeakage and all nd all water is water is flowingflowing through through the weithe weirr opening, (1) place a board across the stream and (2) place opening, (1) place a board across the stream and (2) place another narrow board at right angles to the first, as shown another narrow board at right angles to the first, as shown bel
below.ow. Use a Use a carcarpentpenter's er's levelevel to bl to be sure sure the e the secosecond bond board iard iss level. level. <FIGURE A> <FIGURE A> 42p55a.gif (437x437) 42p55a.gif (437x437)
Measure the depth of the water above the bottom edge of the Measure the depth of the water above the bottom edge of the weir with the help of a stick on which a scale has been weir with the help of a stick on which a scale has been mar
marked.ked. DetDetermiermine tne the he flow flow from from TablTable 1 e 1 on pon page age 56.56. <FIGURE B>
<FIGURE B>
42p55b.gif (393x393) 42p55b.gif (393x393)
Table I Table I
FLOW VALUE (Cubic Feet/Second) FLOW VALUE (Cubic Feet/Second)
Weir Width Weir Width O Ovveerrfflloow w HHeeiigghhtt 3 3 ffeeeett 4 4 ffeeeet t 5 5 ffeeeett 6 6 ffeeeet t 7 f7 feeeett 8 8 ffeeeett 99 feet feet 1 1..0 0 iinncch h 0.0.224 4 00..332 2 0.0.440 0 00..448 8 00..556 6 00..6644 0.72 0.72 2 2..0 0 iinncchhees s 00..667 7 00..889 9 11..006 6 11..334 4 11..556 6 11..8800 2.00 2.00 4 4..0 0 iinncchhees s 11..990 0 22..550 0 33..220 0 33..880 0 44..550 0 55..0000 5.70 5.70 6 6..0 0 iinncchhees s 33..550 0 44..770 0 55..990 0 77..000 0 88..220 0 99..4400 10.50 10.50 8 8..0 0 iinncchhees s 55..440 0 77..330 0 9.9.000 0 1100..990 0 1122..440 0 1 41 4..6600 16.20 16.20 10 10.0 .0 ininchches es 7.7.60 60 10.10.00 00 1212.7.70 0 1515.2.20 0 1717.7.70 0 2020.0.000 22.80 22.80 12 12.0 .0 ininchches es 1010.0.00 0 1313.3.30 0 16.716.70 0 2020.0.00 0 2323.3.30 0 2626.6.600 30.00 30.00 Method No. 3 Method No. 3 The
The float float method method is is used used for for larger larger streams. streams. Although Although it it is is notnot as accurate as the previous two methods, it is adequate for
as accurate as the previous two methods, it is adequate for pra
is smooth and the cross section is fairly uniform for a length is smooth and the cross section is fairly uniform for a length of at l
of at least east 30 ft30 ft.. MeasMeasure wure wateater velr velocitocity by thy by throwrowing ping pieceieces ofs of wood into the water and measuring the time of travel between wood into the water and measuring the time of travel between two
two fixed fixed points, points, 30 30 ft ft or or more more apart. apart. Erect Erect posts posts on on each each bankbank at th
at these pese poinoints.ts. ConConnect nect the tthe two upwo upstrestream poam posts bsts by a levy a level wiel wirere rope
rope (use (use a a carpenter's carpenter's level). level). Follow Follow the the same same procedure procedure withwith the d
the downownstrestream poam posts.sts. DivDivide tide the sthe stream ream into into equaequal secl sectiontionss along the wires and measure the water depth for each section. along the wires and measure the water depth for each section.
In this way, the cross-sectional area of the stream is determined. In this way, the cross-sectional area of the stream is determined. use
use the fothe following llowing formula formula to calto calculate culate the flthe flow:ow: <FIGURE C>
<FIGURE C>
42p56.gif (437x437) 42p56.gif (437x437)
MEA
MEASUSURINRINGG HEAHEAD LOSSD LOSSESES "Ne
"Net Powt Power" ier" is a fus a functnction oion of the f the "Net "Net HeadHead."." The The "Net "Net HeadHead" is" is the "
the "GroGross Hess Head" lad" less tess the "Hhe "Head Lead Losseosses."s." The iThe illullustrastration tion belobeloww shows
shows a a typical typical small small water water power power installation. installation. The The head head losseslosses are the open-channel losses plus the friction loss from flow
are the open-channel losses plus the friction loss from flow through the penstock.
through the penstock. <FIGURE D>
<FIGURE D>
42p57.gif (540x540) 42p57.gif (540x540)
42p58.gif (600x600) 42p58.gif (600x600)
<FIGURE E> <FIGURE E>
Open Channel Head Losses Open Channel Head Losses
The headrace and the tailrace in the illustration above are The headrace and the tailrace in the illustration above are open
open channelchannels s for for transportransportingting water water at at low low velocitvelocities. ies. TheThe walls of channels made of timber, masonry, concrete, or rock, walls of channels made of timber, masonry, concrete, or rock, sho
should buld be pere perpendpendiculicular.ar. DesiDesign thgn them so em so that that the wthe water ater levelevell height
height is is one-half one-half of of the the width. width. Earth Earth walls walls should should be be built built atat a 45 [
a 45 [dedegregreeses] an] anglegle.. DeDesisign tgn themhem so tso thahat tht the wae wateter ler level vel heiheighght ist is one-half
one-half of of the the channel channel width width at at the the bottom. bottom. At At the the water water levellevel the width is twice that of the bottom.
the width is twice that of the bottom. The h
The head lead loss ioss in open open chan channennels is ls is givgiven in en in the nthe nomogomographraph.. TheThe friction effect of the material of construction is called "N." friction effect of the material of construction is called "N."
Various values of "N" and the maximum water velocity, below Various values of "N" and the maximum water velocity, below which the walls of a channel will not erode are given.
which the walls of a channel will not erode are given. TABLE II TABLE II Maximum Allowable Maximum Allowable Water Velocity Water Velocity Mate
Materiarial l of of ChanChannel nel WallWall (feet/s(feet/seconecond) d) ValuValue e of of "n""n" F Fiinne e ggrraaiinneed d ssaannd d 00..6 6 00..003300 C Coouurrsse e ssaannd d 11..2 2 00..003300 S Smmaalll l ssttoonnees s 22..4 4 00..003300 C Cooaarrsse e ssttoonnees s 44..0 0 00..003300 Rock
Rock 25.0 25.0 (Smooth) (Smooth) 0.0330.033 (Jagged) 0.045 (Jagged) 0.045 C Coonnccrreette e wwiitth h ssaannddy y wwaatteer r 1100..0 0 00..001166 C Coonnccrreette e wwiitth h cclleeaan n wwaatteer r 2200..0 0 00..001166 S Saannddy y llooaamm, , 4400% % ccllaay y 11..8 8 00..003300 Lo
Loamamy y sosoilil,, 6565% % clclay ay 3.3.0 0 0.0.030300 C Cllaay y llooaamm, , 8855% % ccllaay y 44..8 8 00..003300 S Sooiil l llooaamm, , 9955% % ccllaay y 66..2 2 00..003300 100% 100% clay clay 7.3 7.3 0.0300.030 Wood 0.015 Wood 0.015 E Eaarrtth h bboottttoom m wwiitth h rruubbbblle e ssiiddees s 00..003333
The hydraulic radius is equal to a quarter of the channel The hydraulic radius is equal to a quarter of the channel
width, except for earth-walled channels where it is 0.31 times width, except for earth-walled channels where it is 0.31 times the width at the bottom.
the width at the bottom.
To use the nomograph, a straight line is drawn from the value To use the nomograph, a straight line is drawn from the value of
of "n" "n" thrthrouough tgh thehe flflow vow velelociocity tty to to the rhe refeefererence nce liline.ne. ThThee point on the reference line is connected to the hydraulic point on the reference line is connected to the hydraulic radius and this line is extended to the head-loss scale which radius and this line is extended to the head-loss scale which also determines the required slope of the channel.
also determines the required slope of the channel. Using a Nomograph
Using a Nomograph
After carefully determining the water power site capabilities After carefully determining the water power site capabilities in terms of water flow and head, the nomograph is used to in terms of water flow and head, the nomograph is used to determine:
determine: *
* The wThe widthidth/dep/depth of th of the cthe channhannel neel needed eded to brto bring ting the wahe water tter too the spot/location of the water turbine.
the spot/location of the water turbine. *
* ThThe e amamouount nt of of hehead ad lolost st in in dodoiningg ththisis.. <FIGURE F>
<FIGURE F>
42p59.gif (600x600) 42p59.gif (600x600)
To use the graph, draw a straight line from the value of "n" To use the graph, draw a straight line from the value of "n" through the flow velocity through the reference line tending to through the flow velocity through the reference line tending to the h
the hydrydrauliaulic radc radius sius scalecale.. The hThe hydraydrauliulic radc radius iius is one-s one-quarquarterter (0.25) or (0.31) the width of the channel that needs to be
(0.25) or (0.31) the width of the channel that needs to be bui
built.lt. In thIn the case case whee where "nre "n" is 0" is 0.03.030, fo0, for exar examplemple, and , and watewaterr flow is 1.5 cubic feet/second, the hydraulic radius is 0.5 feet flow is 1.5 cubic feet/second, the hydraulic radius is 0.5 feet hr 6 i
hr 6 inchenches.s. If yoIf you are u are builbuildinding a tig a timbember, cor, concrencrete, mte, masonasonry,ry, or rock channel, the total width of the channel would be 6 or rock channel, the total width of the channel would be 6 inches times 0.25, or 2 feet with a depth of at least 1 foot. inches times 0.25, or 2 feet with a depth of at least 1 foot. If the channel is made of earth, the bottom width of the channel If the channel is made of earth, the bottom width of the channel would be 6 times 0.31, or 19.5 inches, with a depth of at
would be 6 times 0.31, or 19.5 inches, with a depth of at least 9.75 inches and top width of 39 inches.
least 9.75 inches and top width of 39 inches. Sup
Supposepose, how, howeverever, tha, that watt water fler flow is 4 cow is 4 cubiubic feec feet/set/secondcond.. UsinUsingg the graph, the optimum hydraulic radius would be approximately the graph, the optimum hydraulic radius would be approximately
2
2 feet--or feet--or for for a a wood wood channel, channel, a a width width of of 8 8 feet. feet. Building Building aa wood channel of this dimension would be prohibitively
wood channel of this dimension would be prohibitively expensive. expensive. <FIGURE G> <FIGURE G> 42p60.gif (600x600) 42p60.gif (600x600)
However, a smaller channel can be built by sacrificing some However, a smaller channel can be built by sacrificing some wat
water heer head.ad. For For examexample, ple, you cyou could ould builbuild a chd a channeannel witl with ah a hydraulic
hydraulic radius radius of of 0.5 0.5 feet feet or or 6 6 inches. inches. To To determine determine thethe amount of head that will be lost, draw a straight line from the amount of head that will be lost, draw a straight line from the
value of "n" through the flow velocity of 4 [feet.sup.3]/second to the value of "n" through the flow velocity of 4 [feet.sup.3]/second to the ref
referenerence lice line.ne. Now dNow draw a raw a strstraighaight lint line froe from the m the hydrhydrauliaulicc radius scale of 0.5 feet through the point on the reference radius scale of 0.5 feet through the point on the reference
line extending this to the head-loss scale which will determine line extending this to the head-loss scale which will determine the s
the sloplope of te of the che channhannel.el. In tIn this chis case aase about bout 10 fe10 feet of et of heaheadd will
will be be lost lost per per thousand thousand feet feet of of channel. channel. If If the the channel channel isis