control structures hyda

7/25/2019 Control Structures Hyda

1/8

Rectangular sharp crested weirs - Francis Formula

Sharp Edged Rectangular Weir Sharp edged Rectangular Weir

Full width - modular flow With end contractions - modular flow

Approach velocity neglected Approach velocity neglected

Model 3.1.1 Model 3.1.2

rowning

!eglected

"ectangular sharp crested weir "ectangular sharp crested weir

ischarge #.$## ischarge #.2%#

d&s water level 'mA() #.*## d&s water level 'mA() #.+##

Weir crest level 'mA() 1.### Weir crest level 'mA() 1.###Width , 'm) 3.$$ Width , 'm) 1.###

#.$23 #.$23

ead over weir 'm) #.2## ead over weir #.2*%

/pstream W 0 'mA() 1.2## !um,er of contractions 2

Freefall #.3## 'm) #.+%

Assumptions ead over weir 'm) #.2*%

Approach velocity neglected rror in head over weir #.###

uppressed rectangular weir /pstream W0 'mA() 1.2*%

#.$23 Freefall #.1##

Assumptions

Approach velocity neglected

nd contractions considered

#.$23

Sharp edged Rectangular Weir Sharp edged Rectangular Weir

full width - partially drowned nd contractions - partially drowned

Approach velocity neglected Approach velocity neglected

Model 3.1. Model 3.1.%

rowning

6ons

idered

"ectangular sharp crested weir "ectangular sharp crested weir

ischarge #.3## ischarge #.1##

d&s water level 'mA() 1.#%# d&s water level 'mA() 1.#%#

Weir crest level 'mA() 1.### Weir crest level 'mA() #.+##

Width , 'm) 1.### Width , 'm) 1.###

#.$23 #.$23

#.#%# #.1%#

ead over weir 'm) #.3# ead over weir 'm) #.1+$5f #.3#7 !um,er of contractions 2

5s #.3## 'm) #.+$#7+17

rror in 5 #.### 5f #.1%3

/pstream W0 mA( 1.3# 5s #.1##

Freefall -#.#%# rror in 5 #.###

Assumptions /pstream W0 mA( 1.#+$

If weir fully su,merges and ceases to Freefall -#.1%#

,e a control8 then results inapplica,le Assumptions

If weir fully su,merges and ceases to

#.$23 ,e a control8 then results inapplica,le

#.$23

Notes

1 Input data to cells with ,lue type

2 6alcluation cells in I units.

3 /se #.$23 as default weir discaharge coefficient 'see reference ,elow)

4hese models are of varying comple9ity. For outline design purposes the model 3.1.1 should ,e ade:uate.

% 4he ,right green cell mar;ed freefall refers to the free,oard ,etween the crest of the weir and the downstream water level.

Where this num,er is negative the weir is drowned

'm3&s) 'm3&s)

ischarge 6oefficient 6d


ffective width ,e

6d>

6d>

'm3&s) 'm3&s)



9tent of drowning h2'm) 9tent of drowning h

2'm)

'm3&s)

'm3&s) ffective width ,e

'm3&s)

'm3&s)

6d>

6d>


2/8

Sharp crested Rectangular Weir

harp crested weir for flow measurement

Kindsater-Carter Formula ffective width

,&?

!imensions and head # 2. #.2 2.

Water 0evel 'mA() 1.1## #.2 2. #. 2.*

Invert level 'mA() #.### #. 2.* #.$ 3.$

Weir crest level 'mA() 1.### #.$ 3.$ #.* .1

6rest length , 'm) 1.### #.* .1 #.7 .2

6hannel Width ? 'm) 2.### #.7 .2 #.+ 3.3

head h 'm) #.1## #.+ 3.3 1 -#.+

,&? #.%## 1 -#.+

weir height p 'm) 1.###

Effectie head and crest width 6oefficient of ischarge

'm) #.#++ ,&? a

'm) 1.##3 # #.%7* #.2 #.%7+

'm) #.##1 #.2 #.%7+ #. #.%+1

'm) #.##32 #. #.%+1 #.% #.%+2

!ischarge Coefficient Ce #.% #.%+2 #.$ #.%+3

a #.%+2# #.$ #.%+3 #.* #.%+

a@ #.#1## #.* #.%+ #.7 #.%+$

#.%+3# #.7 #.%+$ #.+ #.%+7

!ischarge #.+ #.%+7 1.# #.$#2

ischarge 5 #.#%* 1 #.$#2

?3$7#Bart A '+.$.1.3) 6hec;s ,&? a@ma9 h&p 2.% o; # -#.##23 #.2 -#.##17

Min h 'm) #.#3# o; #.2 -#.##17 #. #.##%7

Min , #.1%# o; #. #.##%7 #.% #.#1

Min p #.1## o; #.% #.#1 #.$ #.#17

#.$ #.#17 #.* #.#3

#.* #.#3 #.7 #.#%

#.7 #.#% #.+ #.#$

#.+ #.#$ 1.# #.#*%

1 #.#*%

Notes


2 6alcluation cells in I units.3 4his model should not ,e used without reference to ? 3$7#A

? 3$7#A also descri,es the methodology for calculating the flow over notch weirs.

File

Reference

? 3$7# Bart A 1+71 Measurement of li:uid flow in open channels. - Method using thin plate weirs.

Version

#.1 addition of notes

;,

effective head he

effective width ,e

;h

;,

6e


3/8

"road Crested Rect

"road Crested Rectangular Weir

Model 3.2

Freefall #.%## 0oo;up ta,le for 6

#.1 #.2 #.3 #. #.%

"ectangular sharp crested weir #.1 #.7%# #.7%# #.7%# #.7$1 #.7*#

ischarge #.2## 0 #.% #.2 #.7%% #.7%% #.7%% #.7$ #.7*

d&s water level 'mA() #.### p #. #.3 #.7$ #.7$ #.7$ #.7$7 #.7*+

Weir crest level 'mA() #.%## 6 est #.+1$ #. #.7*3 #.7*3 #.7*3 #.7* #.77%

Width , 'm) 2.### #.#7+ #.% #.772 #.772 #.772 #.773 #.7+

#.2 #.$ #.7+2 #.7+2 #.7+2 #.7+ #.+#ischarge 6oefficient 6 #.7%% #.2 #.* #.+#1 #.+#1 #.+#1 #.+#$ #.+1$

ead over weir 'm) #.#+3 6 loo;up #.7%% #.7 #.+11 #.+11 #.+12 #.+1$ #.+2$

/pstream head 'mA() #.%+3 6 error -#.#$1 #.+ #.+21 #.+21 #.+22 #.+2$ #.+3$

1.# #.+2+ #.+2+ #.+31 #.+3$ #.+$

Assumptions 1.1 #.+3% #.+3* #.+# #.+$ #.+%$

Approach velocity neglected 1.2 #.+1 #.+ #.++ #.+%$ #.+$$

uppressed rectangular weir 1.3 #.+$ #.+%1 #.+%* #.+$$ #.+**

6 > #.7%% 1. #.+%3 #.+%+ #.+$* #.+*% #.+7$

1.% #.+$1 #.+$7 #.+*% #.+7 #.++*

1.$ #.+*2 #.+*7 #.+7% #.++ 1.#1#

Notes

1 Input data to cells with ,lue type2 6alcluation cells in I units.

3 4he use of the automatic loo;up ta,le is optional - the value of the discharge coefficient may ,e inputted manually if preferred

4he weir calculation is according to ?3$7# part

% 4he weir is supressed - the crest width is the same as the upstream channel.

$ ?3$7# does not define the performance under su,merged conditions8 however it does define the limits to which the free flow calculations are applica,le - ee Anne9

* A correction for su,merged 'drowned) flow may ,e made according to the reference for drowning of sharp crested weirs.

7 4he ,right green cell mar;ed freefall refers to the free,oard ,etween the crest of the weir and the downstream water level.

Where this num,er is negative the weir is drowned.

+ ?os M.C. Brovides a more detailed discussion of varoius forms of ,road crested weir.

1# 4he shaded areas of the graph are not recommended for measurement purposes.

11 4he ,right green cell mar;ed freefall refers to the free,oard ,etween the crest of the weir and the downstream water level.

File

Reference

? 3$7# Measurement of li:uid flow in open channels Bart "ectangular ?road 6rested Weirs

ee also

?os M.C. ischarge Measurement tructures pp27

Version


h#$p

'm3&s)

h1

h1&p

h1&0


4/8

V Notch Weir

Freefall -#.1##

V Notch Weir V Notch Weir 3.3 Free ischarging !otch 3.3d !otch su,Dect to drowning


Weir crest level 'mA() #.### Weir crest level 'mA() 1.###

u&s head 'mA() #.$2 d&s water level 'mA() 1.1##

/pstream water level 'mA() 1.$3

Angle of root degrees +# 'm) #.1##

#.%7% Angle of root degrees +#

/pstream head a,ove crest #.$2 #.%7%

/pstream head a,ove crest #.$3

5f #.2#2

5s #.2##

rror in 5 #.###

Notes



3 /se #.%7% as default weir discharge coefficient where 4he root angle is +# degrees 'see reference ,elow)

Model 3.3 and 3.3d differ only in the consideration of the drowning of the weir

4he ,right green cell mar;ed freefall refers to the free,oard ,etween the crest of the weir and the downstream water level.

Where this num,er is negative the weir is drowned.

%

$

File

Reference

enderson (pen 6hannel Flow p1*7

Featherstone ".. = !alluri 6. 6ivil ngineering ydraulics pp *# 'drowning)

Version


'm3&s) 'm3&s)

9tent of drowning h2



'm3&s)

'm3&s)

&fis the discharge assuming no drowning

&sis the corrected discharge to account for the drowning


5/8

Rectangular Flu

Flume Flume

Model 3..1 'simplified) Model 3..2 'simplified)

0evel invert Inverts may ,e une:ual

rowning not considered 1.7

6ondition (E

Flume Flume

6hainage #.$## 6hainage 1.###


Invert 'mA() #.### d&s Invert 'mA() #.###

u&s W0 'mA() #.2%* d&s W0 'mA() #.%##

u&s 40 'mA() #.2*7 d&s 40 'mA() #.%#7

'hroat u&s Invert 'mA() #.2##

Width , 'm) #.## u&s W0 'mA() #.$3%

Upstream u&s 40 'mA() #.73*

Width ? 'm) #.$## ump level 'mA() #.3##

0ength 'm) 1.### 'hroat

Area #.1% Width , 'm) #.3##

'm&s) #.$%# Upstream

Froude !um,er Fr #.#+ Width ? 'm) 1.###

0ength 'm) 1.###

epth #.2%* Area #.3%

Einetic head #.#22 'm&s) #.23#

4otal nergy - Flume #.2*7 Froude !um,er Fr #.111

4otal nergy - 6hannel #.2*7

error #.### epth #.3%

Einetic head #.##3

4otal nergy - Flume #.$3*

4otal nergy - 6hannel #.$3*

?3$7#Bart 6 6hec;s "ef error #.###

Min y1 #.#%# o; 1#.$.1

Approach Fr #.% o; 1#.$.2

ma9 ,&? #.* o; 1#.$.2

Min , #.1 o; 1#.$.3 ?3$7#Bart 6 6hec;s "ef

ma9 y&, 3 o; 1#.$.3 Min y1 #.#%# o; 1#.$.1

ma9 y 2.### o; 1#.$.3 Approach Fr #.% o; 1#.$.2

ma9 ,y&?'yp) #.* o; 1#.$.2

Min , #.1 o; 1#.$.3

ma9 y&, 3 o; 1#.$.3

ma9 y 2.### o; 1#.$.3

p refers to the height of the hump

Notes

1 Input data to cells with ,lue type2 Input data in cells with ,lue te9t

3 6alcluation cells in I units

4hese calculations should ,e underta;en with reference to ? 3$7# Measurement of li:uid flow in open channels Bart 6

% 4he chec;s shoen herew refer only to the hydraulic conditions at the flume entry. 4he conditons for the

approach conditons and the roughness and length of the throat must also ,e chec;ed.

$ 4he ratio of depth upstream and downstream as a condition for flow measurement is with respect to the invert of the throat 'including hump if present)

* 4he ? chec;s refer to the undrowned conditions

7 For outline design where the invert is level model 3..1 may ,e used8 however an independent chec; for drowning

of the flume must ,e made

+ For outline design where the invert is may not ,e level and a model 3..1 may ,e used8 achec; on drowning is included in this model.

1# Model 3..3 is similar to model 3..2 e9cept that it includes an estimation of the ,ehaviour of the flume under drowned conditions.

4his estimation is ,ased on the e9it and entry losses to a constriction descri,ed in the openchannel flow models accompaning this spreadsheet

It should ,e used for guidance only8 particularly over the transition ,etween modula and drowned flow. 4he ,oundary is not clear and re:uires cali,ration.

11 Model 3.. is suita,le for use in the cali,ration of flumes provided that all the chec;s in the model are o;

4he method is according to section 1#. of ?3$7#6

4he calculation of the "enolds num,er is using e:uation *2 - Appendi9 6..2 ?3$7#6

If the chec;s are not o; then the method descri,ed in the ?ritish tandard should ,e employed '1#..2H Appendi9 6)

12 4he consideration of drowned flow is evaluated on the assumption that the flume e9pansion is not truncated. ee section 1#.3.1 of ? 3$7#6

13 4he model for open channel flow is included to calculate the ;inetic head for the discharge channel

'which is re:uired for calculating the headlosses through a su,merged flume)

y 'u&s) & y'd&s)'assuming free flow)

'm3&s) 'm3&s)

'm2)

elocity 1

y1 'm2)

v12&2g elocity

1

y1

v12&2g


6/8

Sharp Rectangular +rifice

Sharp Rectangular +rificeModel 3.%

ischarge #.2## Sharp Rectangular +rificeInvert 'mA() *.### Model 3.% 'simplified)

d&s water level 'mA() #.%##

u&s water level 'mA() 1.+31 ischarge #.2##

u&s 4otal nergy 0evel 'mA() 1.+33 Invert 'mA() #.###

d&s water level 'mA() #.%##

!ownstream u&s water level 'mA() 1.+3%

d&s depth -$.%##

d&s depth #.%##

+rifice

(rifice width , 'm) #.2## (rifice width , 'm) #.2##

(rifice height d 'm) #.3## (rifice height d 'm) #.3##

Area #.#$# Area #.#$#

eadloss 'm) 1.31 eadloss 'm) 1.3%Froude !r Fr 1.+3 Froude !r Fr 1.+3

Calculation of Cd (rofice flush with wallsJ y&n n

(rofice flush with wallsJ y&n n uppression ratio #.2##

uppression ratio #.2# 6d #.$27

6d #.$27 6v 'assumed) 1.###

Calculation of C

Appro9imate headlo 'm) 1.3%

Appro9imate upstream depth 'm) 1.+3%

6v 1.##1

Upstream Conditions

/ Invert 'mA() #.###

Width ? 'm) #.$##

depth 1.+31

elocity 'm&s) #.1*

Fr #.#

Einetic head 'm) #.##2

4otal head 'm a,ove invert) 1.+33

Notes


2 6alcluation cells in I units

3 4he suppression ratio refers to the proportion of the perimeter of the orifice that is flush

with the upstream channel. It is calculated from data input a,ove.

%$ 4he upstream head is the sum of the headloss and the downstream head so this structure is not a


7/8

!efined (eadloss ,odel

!efined headloss model

Model 3.$

(*dro "rae

,odel Num.er6hainage #.###

ischarge #.1$%

Invert 'mA() #.###

W0 'mA() #.2##

40 'mA() #.22#


/ W0 'mA() #.77

/ 40 'mA() #.+%

!ownstream

depth #.2##

UpstreamWidth , 'm) #.+##

Area #.3+

elocity v 'm&s) #.3*$

Froude !um,er 1.1

headloss #.277

depth #.77

;inetic head #.##*

40 #.+%

ischarge eadloss 6alculations

m

#.### #.### #.#%# #.#2#

Boint 1 #.#%# #.#2# #.1## #.#%#

Boint 2 #.1## #.#%# #.1%# #.1$#

Boint 3 #.1%# #.1$# #.1+# #.%##

Boint #.1+# #.%## #.21# 1.###

Boint % #.21# 1.### #.2%# 1.3##

Boint $ #.2%# 1.3## #.3## 1.%%#

Boint * #.3## 1.%%# #.%# 2.1##

Boint 7 #.%# 2.1## #.*## 2.7##

Boint + #.*## 2.7## 1.### 3.##

Boint 1# 1.### 3.##

Notes



3 4his model attri,utes headloss according to the discharge as defined ,y the ta,le shown

If ten data points are not needed the siKe of the unused part of the ta,le may ,e left ,lan;

% Features that can ,e modelled include hydro,ra;es and screens and any other e:uipment for which headloss is defined ,y the discharge.

$ (nly one value of depth for a given discharge is accepta,le therefore hystreysis and other comple9 performance cannot ,e modelled - see point $

* 4he


8/8

!efined (ead - !ischarge ,odel

!efined headloss model

Model 3.$

(*dro "rae

,odel Num.er6hainage #.###

ischarge #.1$%

Invert 'mA() #.###

W0 'mA() #.2##

40 'mA() #.22#


/ W0 'mA() #.277

/ 40 'mA() #.3#7

!ownstream

depth #.2##

UpstreamWidth , 'm) #.+##

Area #.2%+

elocity v 'm&s) #.$37

Froude !um,er 1.1

depth #.277

;inetic head #.#21

40 #.3#7

%imit of modula flow

#.%

#.*#

6ondition !R+WNE!

ischarge eadloss 6alculations

m

#.### #.### #.#%# #.#2#

Boint 1 #.#%# #.#2# #.1## #.#%#

Boint 2 #.1## #.#%# #.1%# #.1$#

Boint 3 #.1%# #.1$# #.1+# #.%##

Boint #.1+# #.%## #.21# 1.###

Boint % #.21# 1.### #.2%# 1.3##

Boint $ #.2%# 1.3## #.3## 1.%%#

Boint * #.3## 1.%%# #.%# 2.1##

Boint 7 #.%# 2.1## #.*## 2.7##

Boint + #.*## 2.7## 1.### 3.##Boint 1# 1.### 3.##

Notes



3 4his model returns the head accoring to the head - discharge performance defined in the ta,le.

If ten data points are not needed the siKe of the unused part of the ta,le may ,e left ,lan;

% Features that can ,e modelled include hydro,ra;es and screens and any other e:uipment for which headloss is defined ,y the discharge.

$ (nly one value of depth for a given discharge is accepta,le therefore hystreysis and other comple9 performance cannot ,e modelled.

* 4he limits for modula flow define the limits of applica,ility of the stage discharge performance as defined in this ta,le

File

Version


hydpres.ppt

'm3&s)

y2

'm2)

y1

v1

2&2g

1

Ma9imum allowa,le y2&y

y2&y

1

m3&s

#.### #.2## #.## #.$## #.7## 1.### 1.2##

#.###

#.%##

1.###

1.%##

2.###

2.%##

3.###

3.%##

.###

!efined (ead - !ischarge

,odel /04

!ischarge 2m/$s3

headloss2m3
http://var/www/apps/conversion/Downloads/hydpres.ppthttp://var/www/apps/conversion/Downloads/hydpres.ppt

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